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.

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.

After a successful first mission, the unit get debriefed; McKenzie is carpeted for his actions while Gallagher has to inform Simone's mother of her tragic death. Tightrope walker Soltysyk 'Warsaw' is recruited.