Cornwall, 1930. Bertie Fox has had her dreams of motorcycle racing cut short by a life-changing accident, but now her thrill-seeking ambitions have turned towards the skies. Along with her two friends, Gwenna and Tory, Bertie's joined the flight training school on Pencarrack Moor. When a fourth girl moves onto the base, it's clear she's hiding something from her fellow pilots, even as they try to earn her trust. But the more they get to know the secretive Irene, the more they suspect she might be just as dangerous as she is mysterious.Soon, the three young women uncover something more sinister than they could have imagined. As they're drawn into a complex web, dark pasts and uncertain futures threaten them all and the Pencarrack girls must learn who they can trust, before it's too late.