The Spanish Prisoner

Ingratiatingly small and compact, The Spanish Prisoner fits perfectly into the confines of the home-viewing experience. For once, too, David Mamet the director outshines David Mamet the writer; not since his debut behind the camera, 1987's House of Games, have his characters' clipped speech patterns seemed so much a part of the shadowy world they inhabit. Campbell Scott plays the inventor of a mysterious ''Process'' who gets sucked into a con game that sheds layers like an onion; Steve Martin is all deft, obliging patter as his new best friend; and Rebecca Pidgeon (a.k.a. Mrs. Mamet) gets to invest lines like ''Well, dog my cats'' with soulful inscrutability. Emotionally parched, perhaps, but as satisfying as a really good crossword puzzle. A-