The disaffection Nell develops after his parents and siblings are killed in a car crash probably helps him through the next disaster, as his grandparents and then, it seems, everyone in the world is killed off by a plague that first hits the aged and then works down. Nell experiences the one-day fever but somehow escapes the hideous second stage, a swift premature aging process; from then on he goes methodically about the business of survival, finally tracking down two girls--gentle, passive Lucy with whom he comes to a romantic understanding, and hostile Billie, her companion, who bitterly resents his homing in. Christopher is well known for his post-Disaster science fantasies, but this totally credible adventure, set in a very immediate future, requires no imaginative reorientation. Most impressively, Christopher repeatedly confounds one's expectations of an easy out. The plagueorphaned children whom Nell takes in early on, and who seem destined to break through his protective numbness, age and die before his eyes; the other survivor, probably around his own age, who sends out his address by balloon, turns out to have hanged himself shortly before Nell's arrival--a real jolt, this, but one that shocks Nell into seeking others; and when Billie at last lures him away and tries to kill him, Nell and Lucy pass up the chance to get off on their own, instead taking her back into their lives despite the likely risk and certain aggravation. Of Nell's experiences and encounters only the acquiescent Lucy seems the figment of an adolescent male (and pretty weak) imagination; the rest is compellingly chilly, and real as tomorrow's breakfast.