The French Resistance spot a new German weapons base being developed near Calais. Their sabotage attempt goes badly wrong while a Bomber Command mission also proved unsuccessful. SOE decide this needs a trained unit.

Returning from France, Gallagher begins to compile a team of specialists to train for a one-off mission behind enemy lines. Not everybody is convinced that some can be trusted to follow orders.

Gallagher hands over his new unit to Lt. Col. Squires to begin their training. Scientist Stephen Lovell might be the most vital person on the mission but the army intend to play hardball with him.

Training intensifies with the unit put under extreme interrogation methods to see how they fare. Macaulay's attempted night out becomes a cropper.

The date of the mission is pushed forward when SOE receives new intelligence that the Germans could have up to 14,000 rockets. Final selection is held before paratroop training begins in earnest.

Macaulay's position is in doubt when he struggles to overcome his fear on his first parachute. Rohr is informed that she will go into France as reconnaissance before the main group.

Following a nighttime jump, the unit rendezvous at Pierre de Grouchy's farmhouse. Meanwhile, Gallagher discovers a traitor in the Resistance while former nightclub singer Simone could be recognised.

Major Gallagher discovers a way to cross the minefield which surrounds the German bomb dump.

The deadline for the official selection of the team approaches but tempers flares and quarrels begin.

The team is given a detailed briefing for the attack on the bomb dump but one of team opts out and the operation faces failure.

The team has been briefed and they all recognise the importance of their mission and that their chances of survival are limited.

Gallagher and his team have gained access to the German underground but their entry has been discovered.