Al McGill is a detective with a difference. He's an oceanographer and sometime eco-warrior who tracks flotsam and jetsam back to their source using his knowledge of sea currents. Floating human bodies are his speciality. Two women on different missions seek him out for help. Helen Jamieson is a police officer with a grudge and an unusual case to solve - severed feet wearing trainers are washing up on Scotland's beaches. Basanti, a feral Indian teenager a long way from home, is hunting down the murderers who dumped her friend overboard and abandoned her to die. The loner McGill finds his life and liberty at risk as he also pursues a private quest, the tragedy which first provoked his interest in this macabre line of work: what really happened to his grandfather who was lost at sea?