A daring raid to rescue Dwight from a French jail succeeds--but at great cost. Back in Cornwall, tension fills the Warleggan household after their infant son falls ill; Morwenna is unhappily married off to a vicar; and Aunt Agatha's final words shock George to the core.

The whole family feels the repercussions of Francis's betrayal, although Ross is distracted by a murder that casts suspicion on one of his employees. The crime sends the usually honorable Dr. Dwight Enys into a tailspin of doubt and self-loathing and sets Ross on a course that may ruin the Poldarks.

Trying to improve their financial situation, Demelza puts herself in mortal danger. A newly optimistic Francis pays a high price for his partnership with Ross, and the family seems to be on the brink of ruin once again--until an anonymous benefactor steps in.

Arrested for his role in the shipwreck riot, Ross seems doomed to an unfair trial. Francis seeks to make amends with Demelza, but his guilt over his part in her husband's fall from grace threatens to push him over the edge.

Ross accepts a duel, risking a conviction for murder. Newly pregnant Elizabeth considers extreme measures to safeguard her marriage and family. And Drake makes one last play for a life of happiness with Morwenna.

After her husband's deception, Demelza looks for revenge from some unlikely sources. Tensions run high at home and abroad: the villagers are in open rebellion and war with France lies on the horizon. The discovery of tin at the family mine gives the Poldarks financial stability, but their marriage threatens to collapse.

Ossie and Rowella form a new bond as Ross and Elizabeth rediscover an old one. More interested in social status than romance, George concentrates his efforts on getting elected as the local member of Parliament.

George Warleggan now owns the home of Ross's elderly aunt Agatha. Ross protests to no avail, but George--whose wife, Elizabeth, is pregnant--cannot easily dismiss the ominous words Agatha utters about "a child born under a black moon."

After narrowly escaping execution in France as a spy, Ross continues the search for his friend Dwight. Drake also runs risks as he pursues a relationship with Elizabeth Warleggan's young cousin, Morwenna.

Demelza tries to make peace with Elizabeth and Francis, but her goodwill has grim results. Mad with grief, Ross finds himself entangled in yet another scandal after his attempt at aiding a wrecked ship devolves into chaos and violence.