The film begins when the expat military man Markus has to go home to his teenage daughter Mathilde because his wife dies in a tragic train accident. It seems like a coincidence until the math nerd Otto shows up with his two eccentric colleagues Lennart and Emmenthaler. Otto himself was a passenger on the accident train and is convinced that someone must be behind. As the evidence accumulates, it is clear to Mark that it may have been a carefully orchestrated attack that his wife accidentally fell victim to.