Elizabeth Muir, newly transferred from posh, staid St. Margaret's, has the inexplicable good fortune to be selected by outgoing Paddy Dewar as her best friend--""you two,"" in Gradeside Intermediate School parlance--after a hostile response from other classmates to her innocent shows of superior knowledge. With some nudging from Paddy, and a little discretion on Elizabeth's part, the others begin to accept her too--to include her in games, choose her for teams. And lots of ice is broken by her heirloom snow-scene paperweight. But Elizabeth's sniffy mother isn't at all pleased with Paddy, for all Paddy's delight on her first visit to the Muffs. The girls cause some damage in the garden, which Elizabeth doesn't report; in the heat of a Scrabble game, Paddy swears a little (hell, damn); visiting Paddy's dingy cottage, Elizabeth ruins her dress--and comes home late. She's even begun to stick up for herself: clearly, Paddy is ""a thoroughly bad influence""--and Mrs. Muir decrees that Elizabeth make friends instead with ""sappy,"" pariah-classmate Sylvia Porter, also from a genteel family. Paddy, put off about future visits, catches on--and, in her hurt, tells the other kids. From that moment, Elizabeth is ostracized--save for the unwelcome presence of lithping, tale-bearing Sylvia (who's overheard that Paddy's father's in prison) and her sidekick, pitiful ""Fat"" Spencer. Then Sylvia leaves for a local private school. Elizabeth, who'd come to like Gladeside (and see St. Margaret's shortcomings) before the break with Paddy, begs to go too. But no--""we can't afford it,"" her mother finally admits. (If they hadn't moved, Elizabeth would have had to leave St. Margaret's anyhow.) There's a suspected theft, and Elizabeth defends Paddy to Fat; but when she finds her beloved paperweight broken, everything comes out. . . to be happily (and not unpersuasively) resolved through the clear-sighted intercession of principal Mr. Farmer and Mrs. Muir's admission that she probably did harm by meddling. Elizabeth's despair is palpable, excruciating; Paddy is a surprise mix of sensibility and gusto; Sylvia and Fat and the Muirs, however, run to stereotype. Textured British settings, withal--and compulsive reading.