With an enemy in their midst, can they still protect their fighters in the skies?

Pearl has given up on her dreams of being a journalist after being denied a promotion because of her gender. Joining the WAAF as a radio telephone operator for Bomber Command, Pearl's new job at RAF Fenthorpe serves two purposes - providing an income for her grandmother, and keeping a close eye on her younger sister, Thea, an instrument repairer at another Lincolnshire bomber station.

Pearl befriends Met WAAF Jenny as well as Australian pilot Greg, who she guides home safely during an emergency. Pearl's journalism background doesn't go to waste, however - a series of thefts from pilots rekindles her investigative fire and she is soon caught up in the mystery.

But when all signs point to the perpetrator being her sister, she finds herself up against the clock to prove her sister's innocence ...