S1·E16 The Guided Ones

Dryden discovers the location of the Mystic Valley (and purportedly also, the entrance to Atlantis) in Allen's father's diaries. In the process, Allen confronts his bitterment towards his absent father, and Hitomi discovers her grandmother also visited Gaea. The party is pursued by Folken's floating fortress until Hitomi's pendant and prayer opens a portal to Atlantis.