In Syrenios, Blake, Mortimer and Jessie find housing at the village Café. They then have the happy surprise to see Eleni after she escaped. The next day, the four friends go to the only cave on the island looking for clues of the Christian congregation. They find a kind of decorative fresco that Mortimer found a copy of in the breakfast room of their landlady. During the night, the professor eventually understands that a message is hidden in the fresco and deciphers it. The message directs them to the door of Orpheus, traditionally placed in the cave of Acheruse in Epirus, at the other end of the country. A Turkish smuggler agrees to take them on his old boat but once at sea, they have the unpleasant surprise to find Olrik. A struggle ensues during which the smuggler gets killed, Olrik falls into the water and the boat catches fire. Blake, Mortimer, Jessie and Eleni build a raft and collect Olrik. The next day, they are saved by the yacht of the same couple of British compatriots that had already met Mortimer. They return to Athens but upon their arrival, Olrik escapes from the boat.
