Caris, Mair and English soldiers disembark, shaken by their experiences in France. Nobody heeds the rats that scamper ashore as well.
In Kingsbridge, Prior Godwyn has used the convent gold to start building his palace. Confronted with King Edward's direct order to give it back, Godwyn questions the hasty battlefield scrawl; but he daren't refuse outright. If it's real he could lose palace, priory and head. Afterwards, Caris quietly admits to Cecilia that her initial doubts are complete: she can't believe in a God who permits what she's seen.
Merthin finally reaches Kingsbridge, uncertain of his reception. But at least his old apprentice Jeremiah, who still lives in the house/workshop on Leper Island, is glad to see him. Later he goes to the cathedral, hoping for a glimpse of Caris. Mother Cecilia hopes his appearance will lift her spirits, but to no avail. The ship that sailed can't return, and his unchanged claim of love is unworthy. They have both changed. Better if he accept that and keep his distance.
Ralph gets the chilly welcome he expects from Earl Roland, who still detests him. He isn't pleased to hear that Ralph's war service has won him an Earldom almost as wealthy and powerful as Roland's. Worse, when Ralph meets Philippa and her daughter Odila, she's disgusted to find that his infatuation has grown into a desire for marriage. He's a rapist and murderer; she despises him, and she would die first.
Nate Reeve is redistributing Wigleigh land; too much has lain idle, its owners dead in the war. Most goes to his friend Perkin, even though he can't pay the laborers' on land he owns already. The poorer peasants resent this and, led by Gwenda, come close to riot. Nothing is decided, and Wulfric is notably silent throughout. They squabble on the way home: she insists that he stand up for something, he fears her outspoken ways will lead to trouble - and besides, it makes him look bad. The argument turns to insults, then to violence. As Sam and young David watch in horror, Wulfric knocks Gwenda into the ditch and walks away.
Lonely and depressed, Merthin picks up two whores at the inn. Lonely and depressed, Caris tries to work on her book of medicine. And plague-bearing rats cross the bridge.
At the Winter Feast, everyone is happy or tries to seem that way. Roland drunkenly tries to seduce Petranilla, then insults her age when she refuses his crude advances. Gwenda privately begs Ralph for land so she can be a tenant, not a serf. He refuses, so she asks again, this time on behalf of her son Sam, who is also his. Ralph, shocked, refuses to believe her. Everyone else is shocked still more when Madge's husband sneezes blood. When Caris examines him, it confirms her worst fears. The Mortality has come to Kingsbridge. There are few defenses, but Merthin suggests that the linen masks worn in Florence might have some effect. It's better than nothing.
In Westminster, Edward considers how the plague has weakened the French. Isabella insists this is an advantage, a sign from God, but he points out that the old civil war, the murder of his father, and now this foreign war seem to benefit only her. Perhaps she also knows about the ‘portent' that started it. It's enough for Edward. He sends her away.
Godwyn insists that the Plague is God's punishment for sin -- so comforting its victims is also a sin. Mother Cecilia wants to know what sin a dead child committed - then coughs and sees blood on her hand. Godwyn flees. On her deathbed, Cecilia demands that Caris take her place as Prioress. Godwyn tries to obstruct it with Sister Elizabeth as a rival candidate. He changes his tune about the Plague, now claiming it comes from the Devil, and that God needs no masks to help protect the faithful. Elizabeth is convinced, and rails against Caris's medical idea - until she too sneezes blood and becomes another victim.
When Elfric contracts the disease he hangs himself from his own bridge. Petranilla also falls ill, and when Godwyn finds out he runs away again, not just from his own mother but from Kingsbridge, taking himself, his supporters and (of course the priory treasure to safety. Only Thomas, Matthias and a few other monks remain behind. Caris finds herself Prioress of an almost empty priory.
Petranilla tries to shelter in Shiring Castle, and when she finds it locked against the Plague she tries to buy her way in with information about a son Roland didn't know he had. Instead he dismisses her words as the raving of a woman driven mad by disease.
Godwyn and the treasure take refuge at a forest monastery isolated from people and hopefully plague, but Prior Saul refuses them entrance in case they carry infection as well as gold. He also despises Godwyn for running away from his duty. Terrified and furious, Godwyn murders him, then pretends he has the sickness and has gone into voluntary isolation. Nobody notices that one of the Kingsbridge monks really has the Plague.
Thomas, Caris and the others try to deal with the chaos: masks must be worn, bodies cleared and buried, the town sealed from further infection. Needing authority for these rules, Caris goes to the Bishop for confirmation as Mother Superior; Merthin acts as her escort. On the way he tries again to understand what has come between them. It's simple: the girl he knew is gone -- he doesn't know the woman at all. With so many clergy dead, the Bishop confirms Caris as Prior as well, so when Merthin's mother falls ill, Caris is able to take her confession and learns that one of her sons was an adopted child; only she hears the rest.
Prior Godwyn, completely insane, frantically digs a grave.
And Petranilla sends Earl Roland a rose tainted with her own infected blood.