A rare hybrid of vampire and werewolf, Riley Jenson and her twin brother, Rhoan, work for Melbourne's Directorate of Other Races, an organisation created to police the supernatural races - and protect humans from their depredations. While Rhoan is an exalted guardian, aka assassin, Riley is merely an office worker - until her brother goes missing on one of his missions. The timing couldn't be worse. More werewolf than vampire, Riley is vulnerable to the moon heat, the weeklong period before the full moon, when her need to mate becomes all-consuming...

Luckily Riley has two willing partners to satisfy her every need. But she will have to control her urges if she's going to find her brother. For someone is doing some illegal cloning in an attempt to produce the ultimate warrior - by tapping into the genome of nonhumans like Rhoan. Now Riley knows just how dangerous the world is for her kind - and just how much it needs her.