At the former home of John Lafcadio, the great painter dead some 18 years, the annual ceremony to unveil a painting he left behind to keep his memory alive is interrupted by a murder.

When murder once again visits "Little Venice", Albert Campion must exercise all his powers to bring the killer to justice... John Lafcadio, who modestly described himself as "probably the greatest painter since Rembrandt", has left a bizarre legacy – a collection of twelve sealed paintings, to be unveiled one at a time at an annual event commencing ten years after his death.

While the first seven ceremonies went smoothly, the eighth starts with family ructions, when John's granddaughter Linda finds her boyfriend Tommy has returned from a painting trip to Rome with a model, whom he has married to get into the country.

Nicotine poisoning is diagnosed, and suspicion falls at first on her husband, who had skipped work that day and had returned home for a minute an hour before the body was discovered, only to leave again in a hurry.

Seeking the source of the poisoned booze, Campion and Oates discover that Claire took in wood-blocks for cleaning from Max Fustian, and had returned a parcel that very day.

He learns from the model Rosa-Rosa that Tommy had a cottage in the country, and from the cook Lisa that Lafcadio, despite his determination to defeat his rival and keep his fame alive, had only managed to complete eight of the twelve paintings of his legacy, filling the remaining packages with junk as a joke.