Louise Field Cooper's new novel is as comforting as a heatpad for the joints which begin to twinge over sixty. Hattie, who's well up there, has lived for many, many widowed years in contented isolation, playing ""interior games"" she always wins. Suddenly she's visited by her brother who plans to stay forever in her small New York flat. After two months of encroachment, Hattie makes her breakaway with three dresses, as unnoticeable as she is, and an Altman's tote bag--hopping a bus to Vermont, and going on to Montreal, then England. There she unwittingly becomes involved with two art thieves before she meets a retired engineer who, while married, will also break away. . . . Benignly amusing as it turns unexpected corners, one step removed from Emily Kimbrough and at least three improved.