Hiro a 20-year-old Japanese student sits next to an old man on a train to Berlin. By mistake they exchange phones and read each other´s text messages. Hiro believes that the man´s messages show that he is going to Berlin to kill someone. Hiro´s first day in the city is a race against time as he tries to warn people of an assassination plot. But is the plot real or does it exist only in Hiro´s imagination?