Nazi-occupied France, 1942: In the u-boat port of La Rochelle the crew of U-612 prepares for their maiden voyage when translator Simone Strasser arrives.

On his first mission, captain Klaus Hoffmann drills mercilessly, until the submarine can participate in an attack on a British convoy, only to be called away stat for a secret, super-dangerous mission, which he was chosen for by the gestapo agent as perfect scapegoat if it fails. The French doctor refuses to take more risks for the resistance, only to be defenestrated and have his morphine stolen. Simone is shocked to find herself assigned as translator to the questioning under torture of her roommate-landlady nurse Jaqueline, whom she is ordered to bring the morphine before she's broken, which only works during an air raid. Written by KGF Vissers

Aboard submarine U-612, the atmosphere heats up with the implicit rivalry between 'parachuted son' captain Hoffmann and solid veteran XO Tennstedt, all mistrusting VIP passenger Samuel Greenwood, for whom they has to desert a bloody naval battle and lost another man taking him, who now flaunts being an American opportunistic businessman investing in arms. Frank gets out of favor, nicknamed the Frenchie and deemed neglectful in reporting to the CO. Gestapo officer Hagen Forster invites Simone out privately, even to his home, and to a parade. There the resistance, led by a communist hothead, which rewards Simone with a passport for Frank's secret Jewish bride who hides as brothel waitress, detonates a self-made bomb. The crew gets another shot at a convoy, but a newbie torpedo gunner's arm must be amputated on the spot. Written by KGF Vissers

Aboard, tensions grow somewhat out of control, as cocky macho crewmen rival to be the most unconditional patriots and act on rumors, leading to biter rivalry and abuse, while CO Klaus Hoffmann seeks to learn more and appease. Cynical arms trading US passenger Samuel Greenwood exhausts the officers' patience, until XO Karl Tennstedt actually pushes him in the sea during the delivery to a US freight ship, actually in exchange for ruthless U-boot captain Ulrich Wrangel, who asks in vain to break the gentleman's agreement so both vessels can go home unharmed. Gestapo commissioner Hagen Forster settles for executing the reprisal hostages from a list made after the bomb at the parade nor the crew which beat Frank's secret wife in hospital and caused a miscarriage. Simone tries to look after her while Forster recruits her full-time as his personal translator. Written by KGF Vissers

Having probed and stirred the tension aboard, Ulrich Wrangel legitimates taking command of a mutiny by being 'the highest ranking officer aboard'. XO eagerly sides with him, but honest seamen like Frank openly protest and risk being locked-up before marooning with CO Klaus Hoffmann. Gestapo chief Hagen Forster admits having some personal interest in Simone, ignoring she's the lesbian lover of his now identified resistance target, Carla Monroe, who still pleads bloody methods regardless of innocent civilian victims. Written by KGF Vissers

After maroon evicted the CO and his loyal crew, Ulrich Wrangel's mutineers submarine is hit by an allied depth charge and starts sinking, but not 4 km deep. They are stuck on a sand bank, but panic as the damage is grave and urgent, given oxygen and chlorine gas leaks. Rivalries are put aside as everybody is desperate to survive, even if that means one man must be chosen by straw draw for a suicide mission in the engine room, to salvage the last two batteries. The Gestapo investigation makes great progress, which Simone can report, while curbing Forster's 'inappropriate' romantic moves, to her lesbian lover, the reckless Carla Monroe, who pushes her to take great risks spying. The bomb maker is identified, but killed and evidence removed, leading the collaborating French police chief to conclude there must e a mole, while he steals something. Written by KGF Vissers

While Hagen must inform Simone that Frank's entire crew is missing presumed drowned, the submarine is actually operational again, but nearly out of fuel. So they risk entering the first passing ship. It turns out a Russian trailer, manned by German deserters and Romanians, who hide Jewish refugees. The 'jinx virgin' finally lift his 'curse' by raping the girl. Captain Martin Chaffrof agreed with Ulrich Wrangel to hand over diesel in exchange for repairs, but those prove impossible and an armed conflict kills his crew plus one German seaman. Realizing how close Forster is to catching everyone, Simone calls for all to flee, but Carla Monroe insists to use the last bullets to capture the navy base commander, thus triggering the hostages reprisals commissioner Duval and all others hoped to avoid. Written by KGF Vissers

The crew of U-612 copes with the recent events. In La Rochelle Forster receives bad news. Simone faces a tough decision.