<DIV>Like the yearning, doomed young clones in Ishiguro's <I>Never Let Me Go</I>, three teenagers with XP (a life–threatening allergy to sunlight) are a species unto themselves. As seen through the eyes of 16–year–old Allie Kim, they roam the silent streets, looking for adventure, while others sleep. When Allie's best friend introduces the trio to Parkour, the stunt–sport of running and climbing off forest cliffs and tall buildings (risky in daylight and potentially deadly by darkness), they feel truly alive, equal to the "daytimers." On a random summer night, while scaling a building like any other, the three happen to peer into an empty apartment and glimpse an older man with what looks like a dead girl. A game of cat–and–mouse ensues that escalates through the underground world of hospital confinement, off–the–grid sports, and forbidden love. Allie, who can never see the light of day, discovers she's the lone key to stopping a human monster.</DIV>