Just read: Two-Way Split by Allan Guthrie, 2004, 9780809556519 (US ppbk).
Quite good. This is actually Guthrie's first novel, but the second Kiss Her Goodbye was the first publishd in the States. I read that one a while ago.
Two-Way's story has three different narratives colliding at a post office robbery in Edinburgh. Pearce the recently released convict, Kennedy the bored private eye, and the criminal trio of Eddie, Carol and Robin/Don. Carol is insane and on medication. Robin is insane and off his medication. Don is the split personality of Robin's dead brother and very dangerous.
I like that Guthrie doesn't go into the psychology or pathology of his characters; he presents what is going on and you just have accept it as part of the story until additional explanation is given. The revenge motivations of Pearce - who got 10 years for murdering his dead sister's drug dealer - are revealed bit by bit throughout the novel. But, those bits are not dangled in a teasing - and therefore annoying way - because the action keeps going and hard man Pearce is believable.
Guthrie's third novel is at the library but I have several other books I need to get to first.