Dianne Wiest plays a prima donna proffering an indifference to the world as opaque as the Sophia Loren sunglasses she wears. Her son Thomas, confined to their huge Paris pad, can only gratify himself by sneaking out to meet rent boys while mother’s preoccupied with her latest whine fit. But after a planned tryst is murdered before his eyes à la Dressed to Kill, Thomas leaves home in search of the killer. With Yank Andrew Litvack pinch-hitting for producers Ismail Merchant and James Ivory, Merci is free of much of that M-I pomposity, replacing it with an unnerving drollness. Litvack offers a cameo by Vanessa Redgrave as proof that there’s a prestige picture within all this frivolous melodrama. Non, merci.