The Laughing Policeman, Maj Sjöwall, Per Wahlöö

With its wonderfully observed lawmen (including the inimitable Martin Beck), its brilliantly rendered felons and their murky Stockholm underworld, and its deftly engineered plot, The Laughing Policeman is a classic of the police procedural and "must reading for anyone who claims to be [a student] of the best detective fiction" (Saturday Review).