During one single day a number of life destinies cross one another. It becomes a night for the involved they will never forget, a night when the coincidences are going to change their lives forever.
A woman is found murdered in a closed amusement park. A young couple who happen to be there at the same time become, without their knowledge, suspects for the murder. They are chased by a large number of police but only Martin Beck believes them to be innocent.
In 1981, after the successful test of a submarine tracker device developed by the Swedish scientist Paul Mandell and sponsored by the US government through his representative Miller, his industry is totally burned and the laser device is stolen. Stig Larsson from the Swedish Secret Agency suspects of an inside job and brings the Swedish Marine Thomas Kallin to investigate Paul undercover as his driver. The naive Kallin is double-crossed but continues his investigation while Larsson finds the truth about the heist.
