The Vanishing Point — Patricia Wentworth

Nothing much ever seemed to happen in the sleepy village of Hazel Green apart from the occasional tea party, spiced with local gossip. Until Maggie Bell went out one evening for a breath of fresh air and never came back. Could Maggie's disappearance be linked to security leaks at the nearby Air Ministry? Or is a sinister scheme being hatched closer to home? Miss Silver is called in to solve the mystery just as a second person goes missing...