A serial killer who slaughters campers is on the loose in Sweden. The lead detectives make a breakthrough when the killer, a cloaked figure wielding a sword and a strange mask, sends the police a video recording.
Harry Friberg receives a photo assignment at Lindarängen's airport in Stockholm. The assignment turns into a nightmare when the photographer is invited to a crayfish party by the company's director.
Harry Friberg photographs a mysterious lightning in the water outside the Blockhusudden. The light turns out to flow over a murder.
