Now that their two children have more or less left the nest, UK expatriates George and Margery Ince--a wry, unsloppily devoted couple--are looking forward to calm middle-aging in one of Rome's less scarifying neighborhoods. Margery's a high-toned translator. George is a modest bigwig at the European headquarters of a UNESCO-like agency. The last thing they need is sudden responsibility for a teenage misfit. Nonetheless, Margery can't say no when old chum Tango (a fading Southern belle) begs the Inces to provide a temporary refuge for her runaway daughter Muriel, 16--a ""large, lardy, acne-spotted hulk"" recently retrieved from a Miami-area cult. The girl's been neglected by sluttish, selfish Tango; she's been inanely doted upon by her father, a boorish self-made millionaire; a flouncy finishing school has stifled her natural intelligence. So: won't poor Muriel's visit to Rome be a waste of time all around? No, not at all. Because soon--thanks to Margery's unaffected warmth, thanks to some low-key Pygmalion treatment from a witty, bemused George--bovine Muriel begins to bloom: reading, thinking, studying Italian, soaking up Roman art/history, treasuring the Inces' fondness and respect. True, this newly acquired self-esteem is a shaky commodity--quickly undermined when nasty Tango (back in Miami) jealously picks away at it, when the Inces' own daughter makes a brief, condescending appearance. And, vulnerable again, Muriel allows herself to be quasi-seduced--and quasi-kidnapped--by handsome, bisexual hustler Cesare (who's ""45 going on 12""). Finally, however, after Muriel's parents rush to Rome for the big search--and a dollop of contrived melodrama--there'll be happy-ish endings all around. . .as the former sad sack heads home, college-bound at last. Reveley (A Pause for Breath, 1983) thickens this slight, agreeable scenario with a pair of darker subplots: George's moral wrestlings over expediency (corruption?) at his agency; the decadent/terrorist doings of Rome's spoiled rich kids. Other shadings are provided by the satiric (near-cartoonish) portrait of Muriel's Ugly-American father, by her relationship with the black servants back home, by ironic psychological wrinkles in the George/Margery marriage. But Muriel's coming-of-age remains the pleasant, YA-ish core here, artfully poised between sit-com and sentiment--with modestly involving, mildly amusing results.