After three catastrophic house-sitting commissions, filled with murder and intrigue, the Montgomery house in Blockley seems like a welcome break for fearless Thea and her trusty spaniel Hephzibah. The opportunity to explore the lost Cotswold villages, with only the minor hindrance of checking up on the client's mother, in the adjoining house, promises to be the perfect get away.

But Granny Gladys Gardener, with her conveniently erratic memory and series of ailments that disappear as quickly as they arrive, is a force to be reckoned and is soon arousing Thea's suspicion. After all, why do the Montgomerys lock her connecting door to the house? And why do they set an alarm that goes off every time Granny goes out?