In the penultimate installment of this masterful crime-fiction series, Martin Beck, now head of the National Murder Squad, is called in to a sleepy part of the countryside to investigate a woman's disappearance. What Beck doesn't know is that the woman has already been murdered, her body dumped in a swamp. At the same time, a midnight shoot-out between three cops and two teenage boys ends with one policeman dead.

As Beck and his partner, Lennart Kollberg, investigate both cases, they encounter two figures from their earlier cases. Folke Bengtsson, the convicted killer from the first novel of the series ( Roseanna ), has been recently released. Since that murder shared many characteristics with Beck's present case, Beck comes under pressure to arrest Bengtsson. But Beck has begun to doubt that Bengtsson was guilty of any murder at all. The media swarms over the little town and among the journalists is the man who was convicted of murder in the second novel of the series ( The Man Who Went Up In Smoke ). The presence of these two killers, one who may not be guilty at all and another who killed by accident, raises a theme from previous books: there are different kinds of murder and different kinds of guilt.

The fugitive ''cop killer'' will accidentally provide the solution to Martin Beck's murder case but that's not really important. What matters is the juxtaposition of the sleepy countryside with the violent city and the tension between the ever decreasing number of capable police officers and the growing number of incompetent or corrupt ones.