An inexperienced U-boat crew are plunged into a perilous secret mission, while new translator Simone starts work at the base.

Hoffmann insists on further training despite the crew's desire to head to battle. In La Rochelle, Simone pieces together the previous night's events.

Tennstedt and Hoffmann continue to butt heads aboard U-612, while rebel Carla Monroe plans a mission in La Rochelle.

Unity on U-612 has crumbled and Hoffman and Tennstedt's continued conflict could jeopardise the mission. On land, Simone wrestles with a difficult choice.

A surprise new arrival takes Greenwood's place, causing a divide. Plus, Carla and Simone grow closer and a resistance fighter arrives at the safe house.

Wrangel catches up with Johannes, leading to a dramatic showdown out in the Atlantic. Hoffmann shows up at Cassandra's place.

Hoffmann struggles to hang on as his chance to escape heads toward US shores. Margot pushes on with her plans.