The Laughing Policeman (A Martin Beck Police Mystery)

In this classic police procedural, the ever-dyspeptic Martin Beck has nothing to be amused about, even though it's Christmastime. Åke Stenstrom, a young detective in Beck's squad, has just been killed in an unprecedented mass murder aboard a Stockholm city bus. Was he just in the wrong place at the wrong time, or did he push a murderer too far in his efforts to make a name for himself on the force? Realizing that Stenstrom's presence on the bus was no mere coincidence, his compatriots retrace his steps and chase years-old clues to a crime long thought unsolvable. Along with Roseanna, this is one of the best of Sjöwall and Wahlöö's ten Martin Beck mysteries.