Shetland Sailing Mysteries 2: Trowie Mound Murders

When a couple of yachting tourists go missing from the Shetland oil capital Brae, Cass Lynch is forced to approach her old adversary DI Gavin Macrae for help. He discovers a link between the missing persons and an international art theft, and warns Cass to steer clear - but when one of Cass's own sailing pupils goes missing, she goes alone to discover the secrets of the Neolithic tomb known locally as a "trowie mound".