The Fire Engine That Disappeared

The apartment of a suspect being staked out by Gunvald Larsson explodes, killing three people. Arson and murder isn't at first suspected - much to Larsson's fury - but when it becomes clear that the fire was started on purpose, the case hinges on the needle-in-a-haystack chance of finding a man who fits an impossibly vague description who was somewhere in the area around the time of the fire.