"The Laughing Policeman" by Maj Sjöwall and Per Wahlöö is a classic police procedural novel set in Stockholm, Sweden. The book follows the investigation into a mass shooting on a city bus that leaves eight people dead, including a police officer. The investigation is led by Detective Martin Beck, a methodical and dedicated investigator, who must navigate the complexities of the case while dealing with personal struggles in his own life. As Beck and his team follow the trail of clues and interrogate suspects, they uncover a web of corruption and betrayal that leads to a shocking and unexpected conclusion. "The Laughing Policeman" is a gripping and suspenseful crime novel that delves into the darker side of human nature and the complexities of police work. It is widely regarded as one of the best examples of the police procedural genre and a classic of Swedish crime fiction.