Good pacing, vivid dramatization and strong characterization enliven Spencer's latest work of escapist fiction. When handsome kitchen hand and boat builder Jens Harken audaciously offers to build his employer a regatta-winning yacht, he draws the attention of the master's daughter. Budding beauty Lorna Barnett, disturbingly attracted to Jens despite the restrictions of 19th-century Minnesota's high society, helps him get his chance by breaking down her father's arrogant resistance to new ideas. As the boat takes shape, Jens and Lorna give in to an ill-advised, impossible love that nearly results in a scandal and ultimately requires Lorna to risk the only life she has ever known for the life she really wants. Spencer ( The Fulfillment ) shows the world of the rich in intricate detail, but by failing to provide a similarly full portrait of lower-class society--and the obstacles it places before the lovers--she diminishes her tale's dramatic impact. Her ornate, old-fashioned language, although quaintly evocative of the period, is at times laughably florid, as when Lorna's sisters are described as ``two young sylphs on the brink of womanhood,'' and some of the plot turns are much too neat. Still, the characters' evolution is human and touching. Literary Guild alternate; Doubleday Book Club selection; Reader's Digest Condensed Books selection. (Feb.)