Queen Gaea, mother to Celestia and Luna, has sensed many disturbances over the past few years. She worries about the kingdom she left to her daughters so long ago, and sets out to reunite with them. Her mate, Poseidon, worries for Gaea's safety, and sets out after her. However, things don't go as planned, and dark forces are inadvertently set in motion that threaten the peace of Equestria and the lands beyond.