DCI Lewis investigates a murder when Michael Day's skeleton is found at the bottom of Blackshore Lake. He was apparently killed by a severe blow the head. Oddly they also find an antique hip flask at the site with the name Paul Cochrane engraved on it. The real Cochrane is an odd duck who says he was robbed and has no idea how the flask got to the bottom of the lake. He was once a successful architect and along with some of his old university mates, may have been fishing at Blackshore Lake where Day was found. When Lewis also learns that James Lutton, another member of the fishing group, died on the same date Michael Day went missing, the connection between the two incidents cannot be ignored. As the body count rises, the number of suspects gets smaller and smaller.
—garykmcd