Lachlan Harriot is in a state of shock. His wife Susie has been convicted of the murder of serial killer Andrew Gow, a prisoner in her care. Unless Harriot can come up with grounds for an appeal in two weeks' time, Susie will be given a life sentence, depriving her of her home, her family and her two-year-old daughter.

Harriot is convinced that his wife, a respected forensic psychiatrist, is innocent, and each night climbs the stairs to Susie's study where he goes through her papers, laboriously transcribing onto his computer her case notes, her interviews with Gow and his new wife Donna, and the press cuttings from the trial. But his search for the truth soon raises more questions than answers.

Why had Susie stolen a set of prison files and then lied about it? What was the precise nature of her relationship with Gow? And, most importantly, what is it in her study that she doesn't want her husband to find? As the documents on Harriot's computer begin to multiply, his perception of what really happened between Gow and Susie becomes ever more complex. But first he must decide what he's to do with a discovery that involves violence, sexual obsession, lust and ultimate betrayal.

In her first stand-alone novel following her acclaimed Garnethill trilogy, Denise Mina looks at the shifting sands that separate fact and fiction, perception and reality, responsibility and culpability. Sanctum is a powerful psychological portrait of people living on the edge, an account of the deals with the devil that lie beneath their apparent respectability, and the terrifying journeys they are prepared to make in order to survive.