Isla's mother and father are fated mates who met when Leila was 18 years old. When Isla was 3 her uncle levi( leviathan) took lucifer to take control of the underworld. For 145 years Isla has been helping her mother look for her father. With the help of various people Isla has been training her whole life for the day that they find her father. As lucifer's last act to his family he had a powerful witch cast a spell on Isla and Leila so that they are invisible to the underworld. Isla was tracking a hoard of vampires that has connection to levi and the underworld when she happens upon her fated mate but due to the spell that her father had put on her she cannot sense that he is her mate. Leo must win isla's love without the help of the mate bond and with an ex girlfriend and 3 men from her past in the way. While working on a lead they find location that Levi is keeping Lucifer the only catch is he is being kept in the underworld and allies and enimies alike must work together to set him free.