The deployed military man Markus has to go home to his teenage daughter, Mathilde, when his wife dies in a tragic train accident. It seems to be plain bad luck – until the mathematics geek Otto shows up with his two eccentric colleagues, Lennart and Emmenthaler. Otto was also a passenger on the wrecked train. He is convinced someone must have been behind it. As the clues pile up, it becomes clear to Markus that it might have been a carefully orchestrated assassination, which his wife ended up being a random casualty of.