Police constable Hamish Macbeth is baffled by two apparently unrelated mysteries: a huge quantity of table salt has been stolen from Rory Campbell's general store; and Geordie Robb, a local bully, is missing. Hamish outwits his superiors when he makes a connection between the two mysteries.

Newcomers to Lochdubh Vicky and Paul Jeffreys cause a stir: Vicky tries to put reluctant villagers back in touch with their Highland heritage, gradually alienating them. Hamish investigates when this unpopular, meddling newcomer, receives anonymous threats.

On a mountain trek led by Colonel Don Maxwell, Hamish advises caution once the climbers have reached their goal, but Maxwell urges them on into a dangerous situation.

Hamish turns a deaf ear to the local pirate radio station which is having a remarkable influence on the town. But when the radio authority sends a defector van to close down transmission, he is caught up in a conflict of loyalties.

Personal crisis takes Hamish to a remote island from which he intends never to return. But he is not alone. Meanwhile, his absence from Lochdubh is keenly felt when his over-zealous replacement makes himself a nuisance.

A family feud at the funeral parlour comes to a head. It is suggested that space aliens have snatched a body from the local burial ground.