There's a hitman in Glasgow: unpaid and angry, he's decided to settle his own debts...

Marianne Brogan can't sleep. She's plagued by a nightmare: someone in the shadows, whispering threats, stalking her every move. To make matters worse, Marianne can't get hold of her brother, Billy. Despite knowing some shady characters from Glasgow's underworld, Billy's always been there for her – until now.

Meanwhile, DCI Lorimer and his team are faced with a string of seemingly unconnected but professional killings. Without witnesses or much conclusive evidence to build a case, the officers are drawing a blank. Criminal psychologist Solly Brightman is off the case due to budget cuts. But Solly is more closely connected to the murders than he could possibly know . . . And as the hitman plans a bloody ransom to get his fee, the race is on to find out just who hired him – and who's next on the hit list.