Ryan, the second prince of the werewolf kingdom, discovers that his older brother Damon has secretly imprisoned Adrian, a vampire spy. Convinced Adrian is nothing but a dangerous monster, Ryan tries to kill him again and again—only to have Adrian save his life every single time.
As the Black Thorn Syndicate infiltrates the royal capital and the mysterious Heart Gate prepares to open, suspicion turns into an uneasy alliance. Forced to flee together, Ryan and Adrian forge a forbidden blood bond that ties their lives to one another.
With a conspiracy threatening the throne, his family, and the man he's fallen for, Ryan faces an impossible choice: honor the prejudice of his people by killing the "monster"... or claim Adrian before the entire kingdom as the one he loves.
