The Dark Legacy
Sequel to "The Prince of Darkness"
Things in Storybrooke had been relatively quiet since the dark entity that turned people in the Dark One was destroyed and Robin Hood was its last host. Now a family of six, the Locksley-Mills are happy and content, with only the clash between Regina and Robin and Zelena over little Haven their main concern.
When their daughters turn five, though, they start to worry about the magic inherited from Robin's dark heritage and the power their two little girls have. A strange presence takes an interest in the girls, forcing Robin and Regina to team up with Zelena to protect the children from a cruel fate. Their quest will bring them to a strange and challenging new land--the Underworld.
Stakes are high as our heroes are forced to face their own pasts and what it means for their children's futures as well as their own.