Several months have passed. With their lives on the line, Ross and his friends must launch their most daring plan yet, to save themselves and the country from enemies both at home and abroad.

Demelza discovers the French are smuggling arms into Cornwall. Ross is determined to take vengeance on Merceron and Hanson for framing Ned. Caroline puts her insecurities aside to support Kitty’s battle against Merceron, drawing attention to herself.

Geoffrey Charles makes a desperate plan to elope with Cecily before she weds George, and Demelza uncovers a theft at the mine. With Ned’s trial looming heavy, Ross pleads for Dwight’s help in a daring attempt to save his friend.

Ross returns to London with the Despards and Enyses. Morwenna tackles the grief of being parted from her son. Geoffrey Charles’ intent to marry Cecily lands them both in trouble. George conspires once again against his old enemy.

Ross is given hope for the Despards’ return. Demelza helps the community help itself. Dwight gains unexpected patients. Morwenna begins to secretly slip away from the village. A discovery leaves Geoffrey Charles and Cecily in turmoil.

Ross’ tenacity in helping Ned bears fruit, but at a cost. Demelza wrestles with how best to equip the community to look after itself; Morwenna lends herself to the cause. George’s sanity deteriorates. Cary struggles under mounting responsibilities.