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 unit has now been reduced to six specialists who will participate in the raid. Lovell is determined to quit but no replacement can be found. His superior Professor Evans is brought in to help change his mind.

The unit enters France and discover, from Pierre, that the invasion is a mere two days away. The group head to the German rocket base in Deauville. An RAF bomber raid causes the power to go out, allowing the unit to get in.

The unit have reached the heart of the rocket site. The German kommandant has been made aware that at least three men are on the premises. The group find the documents and plant their bomb but have just sixteen minutes to escape.