Professor David Pollock is an expert in ancient Arabic hieroglyphics. A Middle Eastern Prime Minister convinces Pollock to infiltrate the organization of a man named Beshraavi, who is involved in a plot against the Prime Minister. The nature of the plot is believed to be found in a hieroglyphic code. Beshraavi’s mistress, Yasmin Azir is a mystery intertwined in the plot. Pollock needs her help, but when she repeatedly seems to double cross him in one escapade after another, he can’t decide on whose side she is working. Ultimately working together, Pollock and Yasmin decipher the plot and set out to stop an assassination of the Prime Minister.
Professor Ragheeb (George Coulouris) is taken aback that his regular optometrist is not working, Sloane (John Merivale), a man who he has never met, taking his regular optometrist's place. During the eye examination, Sloane places drops in Ragheeb's eyes, blinding him in pain after a few seconds. After Ragheeb collapses and dies on the floor, Sloane takes off Ragheeb's glasses, and breaks them open to reveal a small piece of paper with crude drawings – seemingly hieroglyphics – on it.At Oxford, Professor David Pollock (Gregory Peck), an American, has taken over an absent Professor Ragheeb's class on ancient hieroglyphics. David makes a crude remark to wake up one of his sleeping students, Fanshaw (Gordon Griffin). At the end of the class, David is approached by Sloane, now referring to himself as Major Sylvester Pennington Sloane, a retired British military man now working as the private secretary for Middle Eastern shipping magnate, Nejim Beshraavi (Alan Badel), who would like to see him immediately on a lucrative business matter. David politely declines without knowing the specifics.David is out for a run when he is ambushed and forced into a Rolls-Royce limousine. He is taken aback by what just happened, until he notices that one of the men in the limo is Hassan Jena (Carl Duering), the Prime Minister of the Middle Eastern country where Beshraavi lives. David is in awe of Jena. The other man in the back of the limo is Mohammed Lufti (Harold Kasket), Jena's ambassador to Great Britain. Jena asks David to accept Beshraavi's offer so that he can find out what exactly Beshraavi's plans are specifically with some opposition to Jena's government policies. In doing this task, David is not to tell anyone he has met Jena, or that Jena is already in Great Britain. There is also some personal risk to David as Beshraavi is a dangerous man. Regardless, David accepts in his admiration for Jena.David meets with Beshraavi in a luxurious and expansive house in London, Beshraavi who has a menacing presence with a peregrine falcon with a penchant to kill if need be. Beshraavi asks David to decode a Hittite inscription – the piece of paper Sloane removed from Ragheeb's glasses – for a payment of $30,000. It should take David no more than a few hours, but Beshraavi gives David a veiled threat that he will be a prisoner at the house until the job is complete.In the library of the house, David is eating individually wrapped candies while he works on decoding the cipher. An exotically beautiful woman who David does not know, enters the room unannounced. She is Yasmin Azir (Sophia Loren), the owner of the house and Beshraavi's lover. Beshraavi, who later enters, infers that David can look but cannot touch with regard to Yasmin, with who he was immediately infatuated.There are four at the dinner table: Beshraavi, Yasmin, David and an English businessman named Beauchamp (Ernest Clark). As Yasmin accidentally knocks over a tray, she is able secretly to slip David a few pieces of paper. David accidentally reveals those papers, Beshraavi who wants to know what they are. David is able to conceal their contents, not wanting to get Yasmin into trouble. David immediately excuses himself, followed closely by Yasmin. Beauchamp and Beshraavi now alone together, Beauchamp remarks that Prime Minister Jena's signing of a business treaty with the British in two days will ruin Beshraavi's shipping business, Beshraavi who, in turn, says that the treaty will not be signed as told to him by a dependable soothsayer.Alone in a bathroom in the house, David reads the two pieces of paper slipped to him by Yasmin, one a news clipping about Professor Ragheeb's accidental death, the other a note from Yasmin asking him to meet her in her bedroom. As David meets Yasmin in her expansive ensuite and she turning on the shower just in case they could be overheard, Yasmin tells David that Beshraavi had Ragheeb killed, and will do the same to David once he decodes the cipher. Their conversation is interrupted as Beshraavi tries to get into the ensuite. As David hides in the shower stall with the water still running, Yasmin lets Beshraavi in. Yasmin and Beshraavi talk about issues such as David's work, and the cipher. Not to arouse Beshraavi's suspicions, Yasmin is forced to take her shower, exposing her naked self to David. Sloane then telephones Yasmin's bedroom phone, he telling Bashraavi that David and the cipher are missing. Overhearing that conversation from the ensuite, Yasmin confirms from David that he has the cipher in his possession. To hide it and without telling Yasmin, he wraps it in one of the candy wrappers he has been eating, a red wrapper with the number "9", which he places in his pocket among some other candy. As some in Beshraavi's employ go searching for David through the house, Beshraavi demonstrates to one of Yasmin's employees, Hemsley (Jimmy Gardner) that he can buy people for their loyalty or else exact extreme revenge. From that encounter, Hemsley tells Beshraavi that he saw David earlier come into this bedroom. Forced to show himself, David and Yasmin emerge from the ensuite, David seemingly abducting her at scissor-point. They escape together, with one of Beshraavi's henchmen, Mustapha (Larry Taylor), on their trail. That chase takes them to the Zoological Gardens, where among other things Mustapha shoots an aquarium, breaking the glass and killing the fish inside. Eventually, Mustapha and David get into a struggle, when a man from behind kills Mustapha. He identifies himself as Inspector Webster (Duncan Lamont) with CID, he who had placed Yasmin's house under surveillance. When a gardens guard approaches asking about who they are and who will pay for the damages, Webster kills him as he would not have been able to show him police identification. Because of this act, David surmises that Webster is not CID, and can't be working for either Beshraavi or Jena. It is then that Webster reveals that he is working with Yasmin.David awakens in the back of a moving panel van after being knocked unconscious by Webster back at the gardens. Webster and Yasmin are now with another man, who is in a loving embrace with Yasmin, he identifying himself as Yussef Kassim. All he wants to know is where the cipher is. David, seeing that they have emptied out his pockets of the candies with the cipher which are now on a shelf in the van, tells Yussef that Beshraavi has the cipher. They decide to use truth serum on David, after which, in a drugged stupor, he talks what they believe is gibberish about the number "9". Believing that he was telling the truth that Beshraavi has the cipher, Yussef tells Yasmin to work on Beshraavi to find out where it is, while they dump David out of the moving van in the middle of the highway. Still in a hallucinatory drugged state, David is almost killed several times over as he largely believes he's a bullfighter and the passing cars are bulls. Eventually, he stumbles across a bicycle and cycles away.The next morning, Yasmin arrives home to Beshraavi's loving embrace. They talk about why David took her hostage – she explaining that it was to escape from Beshraavi's threats to keep him a prisoner at the house until the job was complete – and both David and Mustapha having been killed at Yussef's hands. In the discussion, Yasmin implies that Beshraavi stole the cipher, which was intended for Yussef from Ragheeb, and that Yussef does not yet know the coded message. While Yasmin tells him that neither David or Yussef have the cipher, Beshraavi states that he doesn't have it. He also states that David is not dead, but was seen alive arriving back home on bicycle. Yasmin also tells him that Yussef kept her alive as he thinks she is working with him to get the cipher from Beshraavi. Believing David still has the cipher, Beshraavi sends Yasmin to get it from him as he believes her feminine methods would work better on David than Sloane's more violent ones.At David's apartment, he, still groggy from the drugs, is awoken by the telephone ringing. It is Jena, to who David tells that he doesn't know what's going on with Beshraavi yet, and that he does not have the cipher. Despite his near death encounters, David is reinspired after speaking to Jena. At the end of their conversation, Yasmin bursts into the apartment. Incredulous that she would show up after doing nothing while watching him almost get killed by her "boyfriend" Yussef, Yasmin is able to convince him that she hates Yussef and that the only reason she is in cahoots with him is that his boss, a general back home named Ali orchestrating a military takeover, has her mother and sisters hostage and will kill them if she doesn't cooperate. Likewise, she is only being friendly to Beshraavi on Yussef's orders. She is then able to convince him that what he needs to do is break the code of the cipher so that she can report that information back to the embassy, which will ensure both their safeties. It is then that both realize that neither has the cipher, and that it is still in the back of the van.David and Yasmin are at the construction site Yussef uses as his front. They spot the van. Before they can get to it, they see Yussef then Webster heading for the van. Before the two men leave, Webster, hungry, takes all the candy including the one in which David wrapped the cipher. Following Webster as he eats one candy after another, they pick up the discarded wrappers, to see if it is the red number 9 with the cipher. Some of the wrappers are more difficult to get to than others. They notice that Webster ate the red wrapped number 9 candy and spotted the cipher inside. He goes to a telephone booth to make a call, looking the number up in the telephone booth, meaning that the call is not to Yussef, whose number he already knows. Going to the booth after Webster has left, they see he has scribbled "3:30" underneath the listing for Beshraavi Shipping, meaning that Webster has joined forces with Beshraavi and will be meeting him at 3:30. Knowing Beshraavi's routine, Yasmin knows their meeting place.At Ascot, a decked out Yasmin is with Beshraavi, while a decked out David is looking for Webster. David and Yasmin are able to talk briefly to make plans to meet at 9 o'clock that evening at Trafalgar Square after David gets the cipher from Webster. David spots Webster rendezvousing with Sloane, to who he will hand over the cipher. David is able to poke the paper out of Webster's hand, the paper flying in the air and landing in the middle of the horse track with the horses in a race approaching. As David and Webster scuffle with each other, Sloane gets out a knife to stab David. He misses and instead stabs Webster dead. David risks his life by running out onto the track to retrieve the cipher. He is able to do so just before the horses gallop by, David running away with cipher in hand. This entire situation is visible not only to the entire crowd but more specifically Yasmin and Beshraavi.On a train, David is tracing a copy of the cipher, he who still has not been able to decode it. After he completes the copy, he places the original into a self-addressed stamped envelope which he posts immediately after getting off the train. There, he sees the headlines of the newspaper, which implicates him as Webster's murderer. He telephones Jena for help in this matter, Jena who can offer none except for the advice to stay clear of the police, which David does as he notices a bobby heading toward the telephone booth.Yasmin and Beshraavi are back at her house, he who has bought her several pairs of new shoes. As he helps her try on each pair caressing her legs in the process, they discuss what happened at Ascot. He believes this situation is perfect as she can get close to David, find out what decoded message is from him, and bring that information back to Beshraavi. Beshraavi threatens her in the process, implying that he will kill her if she doesn't succeed.David goes to Ragheeb's house, wanting to speak to his widow (Malya Nappi) as he figures that Ragheeb, who was murdered because of the cipher, may have told her what the decoded message is, or at least mentioned where he got it or have some notes somewhere among his possessions about it. He tells her of Ragheeb's death being murder by Beshraavi. Looking at the copy of the cipher, Ragheeb's widow tears it up in frustration, she finally at least implying that she knew that Ragheeb was working on something dangerous. David also tells her that he is working with Yasmin, her mother and sisters in danger at the hands of General Ali. On this news, Ragheeb's widow states that Yasmin is lying in that she has no mother or sisters, only a father who happens to be General Ali himself.At 9 o'clock that night at Trafalgar Square, David hops into Yasmin's just arrived car and they drive off. They are being tailed by one of Beshraavi's men, but Yasmin is able to lose him. Yasmin, grateful that David is still alive and not in jail, tells him of her discussion with Beshraavi. She asks directly if he still has the cipher. He responds that he no longer needs it as he has decoded the message as, "The peg will not pass until the swans fly high in the kingdom of vesta", he getting much of this made up idea from a billboard they just passed. He says he has done his job, he not needing to know what the message actually means. Rather than she dropping him off for his own safety while she goes to the embassy to report the information, he convinces her that it would be safer for him to stay with her, and that she can telephone the information to the embassy at a pay phone, which she does. She in turn convinces him that she does have to go to the embassy to deal with the aftermath, so he that he needs to find his own way from here as the police at the embassy would arrest him on sight. Following their arrangement to meet at the Knightsbridge Hotel where he is staying, he gets out of the car and she drives away, but he flags down a taxi to follow her. They follow her to Yussef's construction site, she obviously having telephoned him to arrange this meeting. However, hiding in the shadows, David can see Yasmin looking for Yussef in the building, and can see Yussef operating the wrecking ball, he who is planning to kill Yasmin with it. David rushes to save her, just before the wrecking ball comes crashing to where she was standing. Yussef, with wrecking ball, has the two of them on the run through the semi-demolished building, with one near miss after another. David eventually is able to maneuver himself to a spot where the wrecking ball hits an electrical power source, sending a major jolt of electricity through the wrecking ball machine to its cab, electrocuting Yussef to death.As David and Yasmin drive off, they argue, David mad at her for lying about going to the embassy and lying about her mother and sisters, he having got the truth from Ragheeb's widow. Yasmin then figures out why Yussef lured her to the construction site. She tells David that Ragheeb's widow is in cahoots with Yussef, Mrs. Ragheeb who lied to David about Yasmin's family and she who telephoned Yussef to tell him that Yasmin was double crossing him. Learning that Yasmin was telling the truth, David confesses that the story he told her of the decoded message was made up, and that he has not yet decoded it.At David's hotel room, David has worked through the night trying to decode the cipher, while Yasmin has been asleep in the bed. He wakes her up with a loving kiss when he has figured it out. It is not Hittite hieroglyphics as he initially believed it to be but rather a simple children's code. The decoded message is the nursery rhyme "goosey goosey gander", which is probably a red herring for something else. Remembering that Ragheeb's widow tore up a copy of the cipher upon seeing it, David finally realizes that it is not the drawings themselves, but rather something else on the original piece of paper which contains the message. Retrieving the original from the Hammersmith post office where he mailed it, David, in Yasmin's car while she is driving, tries several theories before he hits the jackpot: the cipher was written with dissolvable ink, which leaves the message remaining after dissolved. What remains is a microdot, when under a microscope reveals, "Beshraavi plans assassinate Jena twelve thirty June eighteenth", which is in twenty minutes time. They don't know where to go until Yasmin sees on a newscast that Jena has just landed at the airport. Facing road obstacles, David and Yasmin are able to make it to the airport a few minutes before 12:30. They, however, have problems trying to gain access to the press conference currently taking place. In the background, Jena, who has just been asked by a reporter about the business treaty he is about to sign with the British government, states that he will not be signing the treaty upon review of its contents. Fighting the police and the crowd, David is able to get to Jena and knock him to the ground, when bullets, from Sloane's machine gun, land where Jena was just standing. Jena is grateful to David for saving his life, David in turn telling him that the coded message stated that Beshraavi was going to kill him. Shocked, Jena asks to speak to David in private. Then, Lufti, as Jena is trying to make his way into a private room, shoots Jena dead. Yasmin whisks David off among the melee. She tries to convince him that the man who was just shot is not Jena. David is incredulous to this as he tells her that he knows Jena, has met him, and talked to him several times in the last few days. Yasmin, who now knows the entire picture of David's involvement, knows now that Beshraavi hired this man to impersonate Jena to David, without Beshraavi disclosing to the imposter that it would be a suicide mission. What tipped Yasmin to he not being Jena was that there was no recognition on his face of who she was, she who is a spy working for the real Jena.Making their way to a surveillance truck monitoring all of Jena's movement upon landing, Yasmin asks to see all the footage shot thus far. Reviewing that footage, Yasmin figures that the switch was made in the car transferring Jena from the plane to the terminal, as he was no longer wearing his trademark slippers after emerging from the window darkened car. Rushing off to where the car is located, they notice a large trunk being transferred from the car to a truck, they figuring Jena being inside the trunk. Yasmin figures Beshraavi needed the fake Jena to denounce the treaty before being killed in order to save his shipping business. Able to slip in the back of the truck as it takes off, David and Yasmin open the locked trunk to find the real Jena inside, bound and gagged but otherwise all right. The truck is headed to Yasmin's house and a waiting Beshraavi. The trunk removed from the truck, David, Yasmin and Jena are able to hide inside the truck while Beshraavi and his men transport the trunk to the house. Beshraavi, however, notices that the trunk's lock is broken. Suspicious, he orders the trunk to be opened right then and there, to find it devoid of Jena. By that time, David, Yasmin and Jena are able to run from the truck but are spotted off in the distance. A chase ensues, first through a low wheat field, where David, Yasmin and Jena are tracked by Beshraavi's men in various harvesting machines, one whose thrashing blades almost kill the three. Arriving at the stables, the three are able to secure some horses. At this time, Beshraavi and Sloane among others are following them in a helicopter with machine guns in hand. When the three arrive at a bridge, David figures they have better cover on foot among the bridge's structure. Beshraavi and Sloane are able to get some shots on the three as they race across the bridge, the helicopter making pass after pass underneath the bridge span. Getting to the mid span, the three are forced to stop due to construction work on the bridge. David, standing up to grab a construction site ladder, is an open target for Beshraavi and Sloane's next pass, they who end up missing David. As the helicopter makes its pass right underneath them on the bridge span, David drops the ladder into the helicopter's rotor. Disabled, the helicopter crashes below them into a burning blaze.David and Yasmin are in a romantic mood as they float leisurely in a canoe on a lake. Oblivious to what is going on around them as they kiss and embrace, they crash into a row boat. The male of the male/female couple in the row boat is angry at David, that is until he sees that it is Professor Pollock, the rower being his "sleeping" student, Fanshaw. To get the out of their crashed predicament, David uses a pole jabbed into the lake bottom to push off. He pushes too hard, leaving himself suspended on the pole away from the canoe. David tells Yasmin he can't swim as he falls into the water. Concerned, Yasmin jumps in to save him. "Swimming" David emerges from the water, he telling her that it was his turn to lie in what has been the major characteristic of their shared history. They embrace in the water.