 Barnaby and Troy are called in to investigate at the museum in Aspen Tallow when the painting of a local historical figure, Jonathan Lowrie, is slashed. When the museum s curator is subsequently assaulted and Lowrie s direct descendant is murdered, the detectives must unravel another mysterious knot. Barnaby does focus on one important clue, however: a packet of smoked mackerel inadvertently dropped in the cemetery. Meanwhile, they are joined by Nico, Cully s actor boyfriend, who has landed a part in a TV series as a detective sergeant.