Book Seven. When last we saw Merlin, Luke had imprisoned him in the blue crystal cave. After more than a month of durance Merlin manages an escape, but he’s not content with just gaining his freedom. Merlin journeys to the Keep of Four Worlds and does battle with the upstart wizard Mask. As the duel ends, Merlin kidnaps the paralyzed Jasra (Luke’s Mother) as leverage over Luke, and the adventure only gets stranger from there.