The 15th mystery featuring Hamish Macbeth from the bestselling M.C.Beaton, author of the Agatha series.

Are drugs responsible for a sighting of Nessie's long lost relative?

Recovering addict Tommy Jarret has just rented a chalet to check out reports of a sea monster near the village of Drim. But when he turns up dead, apparently from a drug overdose, Lochdubh constable Hamish Macbeth finds the lad's demise to be particularly fishy . . . and not of the local salmon variety.

Deciding to go undercover, Hamish infiltrates the illicit drug trade in nearby Strathbane. But his scheme springs a leak when he's teamed up with a tough Glaswegian detective inspector named Olivia Chater, aka Concrete Knickers.

For the lanky lawman investigating drugs and sea monsters it's time to sink or swim - and it would be equally dangerous to flounder . . . or fall in love.