Martin Beck, Gunvald Larsson and Alice Levander investigate the mysterious murder of an accountant that was found shot to death at the airport parking. At the same time a reporter receives a package from an anonymous source, with information regarding the embezzling of funds that should have been used for fixing up nuclear reactors. When the reporter contacts Beck, his home gets blown up by a bomb.

Mother of an autistic boy is found murdered in her home. The boy holds the murder weapon, covered in blood.