SO B. IT

Heidi It has gotten to be 12 years old without knowing any but the sketchiest information about her background: her mentally disabled mother, who insists her name is So Be It, showed up with the week-old Heidi on their neighbor Bernadette's doorstep seemingly out of the clear blue sky, and Bernadette, who is severely agoraphobic but also bookish and generous, has been looking out for Heidi and Mama ever since. Somehow Heidi and Mama never get billed for rent or utilities, and besides, Heidi has an almost magical ability to play slot machines, which, in their native Reno, can be found even in the local Sudsy Duds laundromat. But as the novel opens, Heidi has begun to chafe—she is no longer willing to live with Bernadette's complacency about the mysterious past ("What happened before [I met you] doesn't matter," Bernadette tells Heidi. "It's just something to be grateful for") and Heidi is determined to find out what Mama means by the strange word "soof." When Heidi uncovers an old camera with a roll of undeveloped film, a host of clues to her identity send her on a solo cross-country bus trip to confront people who not only do not expect her but have taken pains to insulate themselves from her existence. Suspension of belief is beside the point: readers will probably respond to Heidi's voice and determination, get caught up in the mystery and feel wiser for the mild tear-jerker ending. Ages 10-up. (May)