ONCE UPON A TIME

ABC, 8 ET/PT

This ABC fantasy celebrates its 100th episode mark by launching a story that sends its Disney-inspired characters into the world of Greekmythology. Determined to rescue Hook, his friends follow him into the Underworld, where they encounter people from their past who are not so happy to see them. Which, by the way, is just one of the many reasons the ancient Greeks discouraged trips to the Underworld. Greg Germann, Barbara Hershey and Giancarlo Esposito lead the list of guest stars.