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, Major Hugh Gallagher begins to put together a team of specialists, who he can train for a one off mission behind enemy lines. Not everybody is convinced that some members can be trusted to follow orders.
Major Gallagher hands over his new unit to Lt. Col. Tim Squires to begin their training. Scientist Stephen 'Hibou' Lovell might be the most vital person on the mission but the army intend to play hard ball with him.
The unit are put under a crisis reaction test to see how they act under attack. Training intensifies with the group put under extreme interrogation methods to see how they cope. Capt. Macaulay attempted night out comes a cropper.
The date of the mission is put forward when SOE get new intelligence that the German could have to 14,000 rockets. The final selection meeting is held to see who makes the cut before paratroop training begins in earnest.
Captain Macaulay position on the unit is in doubt when he struggles to overcome his fear on his first parachute. Solange 'Chardonneret' Rohr is informed that she will go into France as reconnaissance before the main group.
Following a nighttime jump the unit meet up at Pierre de Grouchy's farmhouse. Gallagher discovers that there is a traitor in the Resistance while former nightclub singer Simone could be recognised. McKenzie murders a German officer.
After a successful first mission the unit get debriefed. Sgt. McKenzie is carpeted for his actions while Major Gallagher has to tell Simone's mother following her tragic death. Tightrope walker Soltysyk 'Warsaw' is recruited to the unit.
Major Gallagher wants to be relieved of duty due to the attrition rate among the recruits. Scientist 'Hibou' starts playing up, causing friction among the group. 'Merle' and 'Ferdy' start to plan for future together if they survive.
The unit has now been reduced to the six specialists who will take part in the raid. Scientist 'Hibou' is determined to quit and no replacement can be found. His boss, Professor David Evans is brought into help him change his mind.
The unit finally gets into France and discover, from Pierre, that the invasion is just two days away. The group then head to the German rocket base in Deauville. An RAF bomber raid causes the lights to go off allowing the unit to break-in.
The unit are in the heart of the rocket site. The German Kommandant is 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 get out.
