Labyrinth of Beheading (断罪の迷宮 Danzai no Rabirinsux) is the sixteenth episode of Phi Brain: Kami no Puzzle Season One and the sixteenth episode of the anime series overall.
With the planes back to Japan allegedly taken over by the POG, Kaito and the others travel to Venice instead. As Souji goes to see Rook concerning the Phi Brain project, Gammon deduces that their transfer to Italy was the work of the POG and goes alone to take on a Fool's Puzzle, in which he must travel through numbered gates on a gondola. As Gammon reaches near the end of the puzzle, he finds the final gate difficult to reach and the rising tide putting him in danger. However, Kaito arrives and uses his Orpheus state to figure out how to reach the end of the puzzle safely, much to Gammon's annoyance.