December 1924, Karl Denke fails to smite Vincenz Olivier with a pickaxe. He would have been his 31st victim. The film thus reconstructs the mind, motivation, and psyche of its main character in intense dialog between him and the inspector.
Mario, a keen birdwatcher, but unable to drive, offers to pay a man he just meet to drive him from Valencia to Romania. Neither of them is aware of the other's story, but a new and definitive journey starts for both of them.