A killing coast

When a body is found floating in the sea off Portsmouth harbour, Detective Inspector Horton initially judges it to be an accidental death. Soon though, to his dismay, he discovers he's got it very wrong. Accused of being incompetent by his boss, and with the head of the Major Crime Team coming down heavily on him, Horton wonders if he's allowed his ongoing investigation into the disappearance of his mother over thirty years ago to cloud his judgement.