Ever since their birth, siblings Derek and Valerie McCall have always felt alone in the world. Not only are they full-fledged homo novus, the next evolution of humanity, but they are also immortal. This makes it difficult, if not impossible, to form any sort of lasting relationship, whether it's in terms of allies or romance. It doesn't stop them, however, from trying to achieve this goal...when they're not battling vampires, demons, and virtually any sort of threat that faces Earth. Of course they also spend their time locating and shepherding other future homo novus around the world.

The constant toll of the life that they've experienced have taken a toll on Derek and Valerie. Both of them have lost loved ones to violence. Derek lost a wife when she was turned by a vampire, while a boyfriend of Valerie lost his at the hands of chaos demons. As a result, both of them deal with life in different ways; Derek hides his pain under a good deal of sarcasm and anger, while Valerie is more a roll with the punches type of person.

Derek and Valerie have the assistance of Kate Rosenberg, Willow's aunt and a powerful witch in her own right, as well as being Derek's new love. They also have a network of contacts - both outside of work and the Counterpuncher unit inside their workplace, Lone Wolves Investigations. Derek and Valerie's goal remains the same... Using their talents and gifts to defend Earth by any means necessary.