I read the last few chapters of Karen Thompson Walker's debut novel while sitting in my back yard on a balmy June morning. When I reached the end, I looked up at the blue sky and bright sun and realized that the day no longer felt lovely, but ominous: Walker's story had gotten under my skin.

"The Age of Miracles" is both utterly realistic and fantastically dystopian. The Earth's rotation is beginning to slow, and the days are growing longer. At first, it's just by a few minutes, but over time they grow to 60 hours, with the sun dangerously hot for 30 hours, followed by 30 more of dark and cold. Birds die; crops wither, then freeze; whales beach themselves by the thousands. There are blackouts and food shortages.

The government does what governments do -- urges caution and tries to keep order. Stay on "clock time," people are told, and most obey, but fringe groups spring up, trying to live in sync with the sun, and there is strife. And then people start getting sick.

The story is narrated by a 12-year-old California girl named Julia, and her calm, thoughtful voice makes this book shimmer. Julia is frightened by events, but not overwhelmingly so; she is also busy growing up, absorbed by boys, pizza parties and her first bra. Her crush on shaggy-haired Seth Moreno and her parents' bickering are just as important to her -- and so to us -- as the birds dropping from the sky and the Earth's radiation field melting away.

This homey focus keeps the book both bearable and grounded. The big miracles, Walker seems to be saying, may doom the world at large, but the little ones keep life worth living.