The Dark Ones target a living soul for sacrifice, leading to a showdown between Dark Swan and Dark Hook; in a flashback, the Evil Queen forces Hook to confront a demon from his past.
A charged confrontation sends the heroes on a collision course with destiny; Hook's lust for revenge against Gold puts them both in jeopardy; an unexpected evil is released.
Merlin takes Emma on a journey to confront his nemesis; in a flashback, a young Merlin falls in love with a refugee named Nimue.
Crane and Abbie set out to take down a succubus whom Henry has sent out to drain the life forces out of its victims.