I've enjoyed every story I've read in this series, but this is probably my favorite so far. Samantha goes into the Underworld to rescue her sister Nikki. Coming from a family of witches, and having her dad owe a debt to the organizer of the sort of Underworld Games. But Nikki doesn't have any powers and Samantha now did the unthinkable and went into the Underworld by herself to save her.
Good thing for her she runs into Geo. He's been paying a sentence for almost 200 years as a demon, but he is really from the God Realm. He tries to stay out of everyone's way in the Underworld but now he decides to help Samantha get to the Games if she puts in a good word with Gaia so maybe he can finally be free.
They have to go through some crazy adventures to get there and then once they are there they still have to go through more adventures to rescue her sister. But they also have to deal with their attraction. And Geo is one sexy ass demon (not demon)