The fishing port of Carmouth was a health resort on the South West Coast, but for two of the inhabitants, at least, it was to prove the opposite of healthy.

At the seaside resort town of Carmouth, Desmond Merrion is on holiday with his recuperating wife. Merrion soon finds himself investigating several suspicious accidents that befall the heirs of the wealthy Lady Violet Ventham, beginning with the death of a local doctor who might have been tricked into driving his car into the harbor and drowning. Following the second death - a nurse falling from a clifftop path - Merrion is joined by Inspector Arnold of Scotland Yard.