Ray Lennox, is settled back into life with Edinburgh's Serious Crimes team, having fully recovered from his breakdown after the toll of his last investigation. 

When a high-ranking member of the establishment is found dead in a Leith warehouse, Lennox is thrown into a case which quickly reveals itself as the work of a serial killer. As victims mount up, Lennox realises these are anything but random. This is the work of a solitary killer with an axe to grind. Never far from his psychological turmoil, Lennox is pushed back towards his demons by this new case.