The spy coast / Tess Gerritsen.

Maggie Bird is many things. A chicken farmer. A good neighbour. A seemingly average retiree living in the seaside town of Purity. She's also a darned good rifle shot. And she never talks about her past. But when an unidentified body is left on Maggie's driveway, she knows it's a calling card from old times. It's been fifteen years since the failed mission that ended her career as a spy, and cost her far more than her job. Step forward the 'Martini Club' - Maggie's silver-haired book group (to anyone who asks), and a cohort of former spies behind closed doors. With the help of her old friends - and always one step ahead of the persistent local cop - Maggie might still be able to save the life she's built.