DI Jim Carruthers has to put his personal feelings for newly- appointed DCI Sandra McTavish aside when a young student is brutally attacked and left for dead. Meanwhile, when a university lecturer is stalked by one of her own students, Carruthers is horrified to discover that the academic is none other than his ex-wife, Mairi. Are the attacker and stalker one and the same, and if so, will Carruthers' ex-wife be next? When a second then a third victim is discovered, not only dead but mutilated, Carruthers and his team are tasked with searching for a murderer. A murderer who takes great pleasure from killing. What is the victims' connection to a cult in North America, which seems to be getting a stranglehold in a Scottish university? Why have these women been targeted? And who is doing the killing? It looks like there might be a serial killer on the loose in Castletown but can DI Jim Carruthers stop this depraved murderer before they strike again?