"As tensions rise, they must stay close together and patrol the DC streets at night, seeking signs of the Harbinger, an entity that is killing Wardens and demons with no seeming rhyme or reason. Forbidden to be with each other, Zayne and Trinity fight their feelings and turn to unusual sources for help -- the demon Roth and his cohorts. But as deaths pile up and they uncover a sinister plot involving the local high school and endangering someone dear...

Marlow Green is a high school boy in New York who is always in trouble for vandalism and acting out, until one day he stumbles into the middle of a battle with a demon, and learns about the Devil's Engine--an ancient machine which can grant anything you wish for, in exchange for your soul.