The shoe that Valerio found on the banks of the Tiber actually has traces of another place. As the former scientific colleague Alessandro explains to him, Ettore may have found himself in one of the quarries in Tivoli. Valerio asks Arturo, a retired canine agent, to accompany him along with the Gandalf hound. In a stretch of water in the quarry he finds a shirt that belonged to Ettore.
—Canon y mus