Lynn and Zach are not exactly human but the other doesn't know till Lynn is almost killed in battle. Kate and Gary are humans but get pulled into the supernatural realm by Lynn when she is shot and heals before their eyes. Lynn and Kate have been best friends since their freshmen year of highschool but Kate doesn't know about Lynn's ability till Lynn is shot in the chest during a tour in Iraq. Zach and Gary meet during basic training and later end up in Iraq with Lynn and Kate moments before a single shot is fired.