My Old Lady Kevin Kline, Maggie Smith, Kristin Scott Thomas. Directed by Israel Horovitz. Rated PG-13. Opens Friday.

My Old Lady starts out with a sitcom-style setup, as broke American screw-up Mathias Gold (Kevin Kline) arrives in Paris to claim the apartment he’s inherited from his late father, only to discover that it’s occupied by an irascible nonagenarian Englishwoman named Mathilde Girard (Maggie Smith), who’s guaranteed occupancy in the place until her death, under a French real estate deal known as a viager. With no money and nowhere to go, Mathias moves into the apartment with Mathilde and her adult daughter Chloé (Kristin Scott Thomas), biding his time until he can sell the place.

Although the conflict between the cynical Mathias and the tart Mathilde is initially played for gentle laughs, writer-director Israel Horovitz (adapting his own play) has more serious intentions. As buried family secrets come to light, and Mathias, Mathilde and Chloé all have to deal with their own inner demons, the movie turns somber, while retaining some of its earlier whimsy. The mix of tones is a bit jarring, especially when the movie wraps up by lightheartedly brushing aside many of the complex issues it introduced in the second half. Kline, Smith and Thomas all do solid work with both comedy and drama, but the movie fails to make either mode entirely convincing.