Festival season. The streets are filled to bursting with tourists, and Edinburgh is gripped by a stifling heatwave. Not the best time for one of the most violent murders the city has witnessed in years.

The victim of the murder cannot be identified; its brutal nature of the shocking both the public and the police. What could possibly have inflicted such gruesome injuries? Was it a wild animal on the loose, or the beginning of some horrific gang warfare?

Another body is found on Musselburgh Beach: naked, comatose, but this time still alive.

DI Tony McLean can't shake the feeling that there is a connection to the killing - but there are few leads for him and the team to go by. The police are at a loss, and the city is on edge - will the killer strike again?