Joerns' perky pictures, in fresh, sharp colors, combined with her live-wire animal characters, give this latest effort the eye-appeal of its predecessors (The Forgotten Bear, The Foggy Rescue). And there's no let-up, certainly, in the action. But the tale--pegged on unwanted pup Oliver's search for a home--is a shaky combination of whimsy, fictional stereotypes, and bare-faced contrivance. When his cage is left unlatched, Oliver escapes from the pet shop where (for no certain reason) he's remained unsold. With every door closed to him, he takes refuge in a hole under a stoop; there, he's attacked by cat Tiger, whose ""house"" it is (but ""Oliver could not read the sign""), on suspicion of eating Tiger's ""leftover""--which turns out to be mouse Moby. Next morning, Moby shows him the way to the butcher shop, source of sustenance for stray dogs; the street's other strays try to seize his bone; he fetches up in a fancy, butler-equipped domicile--where the near-sighted old lady of the house mistakes him for a baby and togs him out accordingly. Then, wheeled through the park in a carriage by the butler, he's set upon by those same strays, ""looking for his bone,"" and in the ensuing mÃ‰lee finds himself, with mouse Moby, in the river. . . from which he's rescued by a boy. . . who gives mouse and dog the names Moby and Oliver and wants them for his own. It all stretches credence a little too thin--and undermines the appeal of Oliver's plight in the process.