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.

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.