The Ashfordly team join forces with DS Dawson and a shady MI5 agent in the hunt for a Russian trawlerman suspected of being a spy, but Carol soon discovers the government worker has secrets of his own after witnessing a shocking stand-off at a railway station. Meanwhile, Aunt Peggy fancies herself as Aidensfield's very own Miss Marple after an old note among a dead friend's belonging raises questions about her cheating husband's disappearance, whilst Miller is suffering from a terrible toothache.

Rob clashes with Blaketon when he struggles to decide whether an ex-Army major is guilty of murder after shooting a youth who broke into his home. Meanwhile, a struggling father asks Carol to try to get through to his pregnant teenager daughter who has shut herself off from the rest of the world, whilst Peggy incurs Bernie's wraith when she, Rosie and David try to save the garage from a financial crisis by giving it a modern makeover.