Derkus Petronicus or "Derk" assassinated a public official named Lycus in Sparta. According to Derk, Lycus had killed (presumably unfairly) the sons of a woman in Attica. He escaped only to have Hercules hunt him down. Hercules accompanied him on the prison ship Enyalios back to Sparta to ensure Derk would get a fair trial. En route, the ship capsized in a storm and Hercules and Derk were washed ashore on an island inhabited by deadly Sand Rays. They finally managed to escape on a pirate ship.