'Fitz' Fitzgerald (Robbie Coltrane) is an insulting, nosy, loathsome individual who is a drunken excuse for a husband, a lousy father, and a gambling washout but he has one saving grace - he is a brilliant psychologist with an uncanny ability to see evil in people, make them confess and walk away unscathed. He seems to understand the criminal mind, most probably because his mind isn't that far removed from the criminals he deals with.