Set during the time of the first outbreak of bubonic plague in England, a young monk is tasked with learning the truth about reports of people being brought back to life, a mission that pulls him toward a village ruler who has made a dark pact with evil forces.
Black Death begins with a voiceover from Wolfstan (John Lynch), a soldier in the employ of the Church in 13th Century England. As an enforcer of the Church's will, Wolfstan is one of a group who roots out and hunts down all traces of infidelity and sacrileges against God. The opening voiceover talks about the bubonic plague decimating life across England. Many people believe the plague is a divine punishment sent by God to scourge the unfaithful, but Wolfstan questions what amount of sin would warrant a punishment as cruel and merciless as the plague. He believes the plague is the result of people in league with the Devil, and he and his fellow soldiers must hunt down and destroy those devil worshipers responsible for the plague.Osmund (Eddie Redmayne) is a young novice monk going into a nearby town on an errand. He stops to see Averill (Kimberley Nixon), a beautiful young woman who is in love with him. Osmund convinces Averill to leave town because of the plague's spread. He wants her to run and hide in a forest. Averill begs Osmund to go with her, and tells him that she will wait one hour each day, at dawn, by a particular landmark in the forest, for one week. After that she will know he is not coming.Osmund is torn between his love for Averill and his vows to God. Back at his monastery, he falls to his knees and prays fervently for a sign that will help him choose.A day later, a troop of Church soldiers arrives at the monastery. The soldiers are led by Ulrich (Sean Bean), an aide to the local bishop. Ulrich and his men, including Wolfstan, are on their way to a remote village at the edge of a large marsh, to investigate stories that it is free of the plague. Ulrich is at the monastery to conscript one of the monks as a guide to lead the soldiers through the marsh to the village. Osmund, having grown up in the area, sees this as the sign he prayed for, as the expedition must pass through the forest where he sent Averill into hiding. He eagerly volunteers to guide the soldiers.Along the way, in the woods, the soldiers pass by a group of villagers preparing to burn alive a woman suspected of witchcraft (Marianne Graffam). Ulrich interferes and unties the woman, leading her away only to cut her throat with a dagger. He tells Osmund that as soon as the soldiers left, the villagers would have promptly seized the woman again and carried on with the execution. The woman was as good as dead when they encountered her, and all Ulrich could hope to do was make her death painless and quick.They are passing through the forest where Averill is in hiding and make camp. At dawn, Osmund hurries to the landmark where Averill told him to meet her. He finds only her scarf and a group of bandits. Osmund makes it back to the camp, but the brigands track him there and attack the soldiers. The soldiers slay most of the brigands, but a few manage to escape — with the soldiers' horses, forcing them to go the rest of the way on foot.They arrive at the village and are greeted by Hob (Tim McInnerny), who welcomes them when they say are travelers seeking shelter for the night. Osmund, who is wounded, receives treatment from the town herbalist, Langiva (Carice Van Houten). They are all invited to dine with the villagers in the evening. But slowly signs start to come out that things are not as they appear in the quiet, peaceful village. Langiva saw right through Ulrich's story, as she tells Osmund. Seeing a look about him, she trusts him with knowing that she harbors a resentment toward the pious and holy, as they killed her husband. Shortly before dinner, she brings him to a field where a number of scarecrow-like effigies are on stakes — but Langiva tells Osmund that they are in fact the remains of the last Church party that sought to kill them for perceived heresies and sacrileges. Then she reaches into what appears to be a shallow grave… and pulls out Averill.Ulrich has found an idol that, to him, is proof that the village is without God — and for that, they must all pay.But it is Ulrich and all the others who about to be betrayed. Their food and drink, at the dinner, was drugged. They all come to at dawn, bound in a deep trough filled to their waists with water. All the village is gathered around, and Langiva is to preside over THEIR trials. The village has become strong in its sense of community and having all renounced God. Now they intend to do the same with the soldiers, all of whom are defiant and ready even to wrestle each other over the 'right' to die first in God's name. The village chooses Frith (Thorsten Querner) to be first. They bind him to a cross, ready to kill him slowly and painfully unless he renounces his faith. But Frith's profession in the Church is a torturer; he inflicts torture on perceived heretics, witches, and those accused of being ungodly. He proves that there is nothing they can teach him about pain, and finally they simply disembowel him. The next soldier chosen, his morale broken, renounces his faith and God before the village, whereon Langiva says that three villagers will escort him to the outskirts and let him go free– a lie, as he is hanged like a common criminal from the trees just outside the village.Langiva directs Osmund to go into a particular nearby house. She still sees him as a potential convert to the village's independent, atheistic way of life. Osmund finds Averill inside. She is in a deep, deep stupor, barely coherent, but she is alive. Still, to Osmund, it appears very much that her mind is gone; he believes Langiva has used dark witchcraft to make Averill into a zombie. Grieving and desperate to see Averill spared any pain and suffering, he takes a knife and grants her release through death, carrying her body out back to the village square.Langiva, angered by Ulrich's continued defiance, has him bound between two powerful draft horses to be drawn and quartered. Hob, instead of letting Ulrich be torn apart, has the horses pull enough to stretch Ulrich like he is on a rack, torturing him. Ulrich appears to break and begs that Osmund be allowed to administer last rites. As the young monk begins to do so, he removes Ulrich's outer garment.Ulrich's body is covered with large, bleeding sores. He has contracted the bubonic plague, and has now brought it to the village as his instrument of dark justice for its ungodliness. The villagers begin to scatter, spooking the horses, who tear Ulrich apart. The remaining soldiers manage to grab a dropped knife, cut themselves free, and overpower the remaining villagers. Hob is captured alive and most of those who remained are killed. Of the soldiers, only Wolfstan survives.Osmund runs after Langiva and accuses her of killing Averill. Langiva answers that she has no powers, no sorcery; she is merely an extremely skillful herbalist who used some 'parlor' tricks with her mastery of herbs and her ability with verbal persuasion, to give the villagers confidence and independence. She is not a witch, merely a good leader. She insists she did not kill Averill; she had found her alive in the forest and merely kept her drugged as part of the plan to convert Osmund. As she walks away, Osmund begs Langiva to bring Averill back, but she coldly tells him she has no power to do so; she scornfully suggests he pray to God and ask Him instead.Wolfstan places Hob in a restraint device hooked up to the wagon they brought. He is bringing Hob back to the Church to be put on trial as the village necromancer. But, as he explains in a voiceover, he knew that Hob was not guilty of witchcraft or any form of demonic consort. The village remained free of the bubonic plague not through witchcraft or necromancy, but merely by its remoteness from the rest of civilzation. Once Ulrich was found to have brought the plague to the village, any of the villagers who didn't die in battle with the soldiers were quickly wiped out by the illness.Wolfstan brings Osmund safely back to the monastery en route to the Church. Although he prays for Osmund to have a long, peaceful life, a series of voiceovers provided by Wolfstan show that Osmund's life became anything but peaceful. Wolfstan explains that he never saw Osmund again, but heard the terrible stories:Averill's death left Osmund nearly mad with grief. Desire for vengeance on Langiva turned his heart stone cold, and he took up the sword as an inquisitioner for the Church, leading merciless crusades against perceived witches. He saw Langiva's face in every woman who was tortured and killed at his command. He is shown delivering a terrified young woman to a dungeon, where she is brutally tortured; he watches impassively as her toes are crushed with metal pliers, and orders her to be killed when she still does not confess to heresy and witchcraft.Wolfstan's closing voiceover offers a prayer that Osmund somehow found peace in his work, as Osmund is seen presiding over a dark execution where a young woman suspected of witchcraft is dragged in terror from the village fields as she is working there, and burned alive. Fade to black.