David Mamet’s second feature as a director, coscripted with Shel Silverstein, is a little bit of a letdown after House of Games, but as a Mafia fairy tale with a tour de force performance by Don Ameche (soft-pedaling all the way), it is certainly watchable and enjoyable enough in its own right. Over a weekend, a low-ranking Chicago mobster on probation (Joe Mantegna) is asked to coach and chaperone an elderly Sicilian shoe-shine man (Ameche) who, in exchange for money, has agreed to take the rap for a murder he didn’t commit. He decides to take the old man to Lake Tahoe for a final fling before he goes to prison, at which point a series of misunderstandings leads to the Sicilian being mistaken for a big-time Mafia chieftain. Basically a low-key comedy, this exhibits some of the same tart, triple-distilled flavor of Mamet’s dialogue in earlier efforts; what disappoints after the darker and harder edges of House of Games is a slight veering toward slickness and a touch of sentimentality. Despite some attempt to be “cinematic” here, Mamet’s talk is still his strongest suit. With Robert Prosky, J.J. Johnston, Ricky Jay, and Mike Nussbaum, all effective (as is Mantegna). (Chicago Ridge, Golf Mill, River Oaks, Woodfield, Yorktown, Evanston, Fine Arts, Hillside Square)