Burnt out after ten years at the chalkface, Lucy's taken a sabbatical from her job as a history teacher to focus on some research. She moves to a tiny Cotswolds cottage that comes with a reduced rent in exchange for keeping a daily eye on Bunty, an extremely feisty ninety-something. She arrives at the cottage with boxes, bags and her faithful West Highland terrier Hamish, but Bunty claims to know nothing about the agreement - it's been arranged by Margaret, her interfering daughter-in-law.
Lucy's only goal is to relax and focus on doing some research on the women of nearby Bletchley Park. But the villagers of Little Maudley have other ideas, and she finds herself caught up in the campaign to turn the dilapidated telephone box at the heart of the village into a volunteer-run library. In the process, she makes friends with treehouse designer Sam, and finds herself falling for the charms of village life. Bunty slowly warms to Lucy, and confesses that the telephone box has special memories for her - it's the place where she used to exchange secret messages with a Canadian airman stationed near by during the war. But that's not the only secret Bunty has been keeping for all these years . . .
Meanwhile Lucy's new friend Sam is trying to get to the bottom of the sudden change in his teenage daughter Freya. He's hoping that Lucy might help him uncover what's going on and why she is keeping secrets of her own.
As Lucy and Sam uncover Bunty's story and the sleepy village's part in the war, their friendship grows and grows . . .