Former Atlantic Monthly staffer Stacey makes her debut with a sharply observed, deeply personal account of her son Walker's metamorphosis from a worryingly unresponsive infant to an intelligent, normally functioning child. Living in the leafy college town of Northampton, Mass., Stacey documents her harrowing experiences as a mother, as she and her husband, Cliff, quickly realize that Walker is not a normal, happy baby. Walker fails to respond to his parents, eats very little, is unable to express emotion and spends much of his time staring at windows. Stacey works night and day to try to reverse Walker's diagnosis of possible autism, trying every conceivable treatment and specialist and obsessively educating herself about new trends in the neuroscience behind the disorder. She realizes that Walker blankly stares out of windows not because his senses are dulled but because they are overwhelmed; Walker is hypersensitive to the world and cannot cope with the constant rush of stimuli. Child psychiatrist Stanley Greenspan recommends his controversial "floor time" strategy for Walker: several hours of rigorous playtime between parent and child per day, emphasizing interaction. The time, money and stress involved in maintaining an intensive schedule of treatments for Walker from his eighth to 20th month soon show their toll on the Stacey family, as funds run dry, the parents grow further apart, and less time is available for Walker's older sister, Elizabeth. Stacey in particular becomes increasingly nervous, obsessive and exhausted from her constant battle to improve her son's life, but the result is stage-by-stage breakthroughs. Some readers will want less personal and medico-historical detail and fewer in-depth treatments of the various therapies and sessions, but Stacey keeps the focus on her own understanding, which ultimately sustains the book. (Sept. 15)