After an irate Warleggan and his henchmen punish Jud for his loyalty to the Poldarks, Ross's simmering dislike for George boils over into violence. Demelza has some surprising news, but her husband's reaction is even more shocking.

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.

While Demelza remains in misery at her father's home, the Poldark family is struck by bad fortune and a series of tragedies. Elizabeth flees her unhappy marriage and runs to Ross to rekindle their romance, but Demelza's secret threatens to come between them.

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.

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.

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."

Limping and scarred, Ross Poldark returns from the American war to Cornwall after a daring escape from a French prison camp. He finds his debt-ridden father dead, his estate in shambles, and his beloved Elizabeth engaged to his cousin Francis.

Drake disappears, suspected of murder, and George's plans to hurt Ross begin to take effect. But it is the actions of Demelza that not only nearly bankrupt the Poldarks, but also put Ross's life on the line.

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.

Members of the Warleggan and Poldark families become mired in jealousy. George takes out his hatred of the Poldarks on poor Drake Carne, but it is the gentle Morwenna who proves particularly ruthless in exacting retribution and getting just what she wants.