The Day That Everything Changed.Five years ago, an unexplained accident results in the spread of billions of incomplete microscopic nanites into Earth's atmosphere. The nanites infect all living things and randomly activate, causing some organisms to mutate into Exponentially Variegated Organisms, or EVOs. In response to the Nanite Event, an international organization known as Providence is formed to contain the EVO threat. Rex, a 15-year-old boy, is an amnesiac EVO in Providence's custody who has the ability to control nanites, allowing him to both cure some EVOs and manipulate his own nanites to form biomechanical weapons from his body. Under the supervision of Agent Six and Providence head scientist Dr. Rebecca Holiday, Rex deals with EVOs around the world, curing as many as he can. Tiring of Providence's control over his life and poor treatment of him, Rex sneaks out of their headquarters with his EVO chimpanzee friend Bobo and meets Noah Nixon, an ordinary teenage boy whom he befriends. The two are then attacked by a group of EVOs who pull them through a portal to Abysus, an EVO-infested Eastern European country, where they meet Van Kleiss, the EVO leader of Abysus with the ability to manipulate its environment. Van Kleiss explains that Abysus was the epicenter of the Nanite Event, and heavily implies that he knows Rex and that he was involved with the events leading to the Nanite Event. Van Kleiss then attacks Rex, revealing that he feeds on fresh nanites. Rex escapes, and Agent Six arrives to rescue the group, with Rex killing Van Kleiss during their escape, but Van Kleiss regenerates his body. Later, at the Providence HQ, Six and Holiday promise to treat Rex better and help him uncover his past, and Noah is revealed to be secretly working for Providence's leader, White Knight, to spy on Rex.