Colin Firth stars as Stanley Crawford, a world-renowned illusionist in 1920s Europe who works under the exotic stage persona of Wei Ling Soo, a master of magic from the Orient. With his embroidered chinoiserie robes and diabolical Fu Manchu mustache, he mystifies audiences with his seamless sleight of hand. Backstage, though, when he reverts to being Stanley, he’s just an arrogant British stick-in-the-mud who dismisses his audience as a bunch of dim-witted suckers. How could any reasonable person possibly believe in magic? So when a magician friend (Simon McBurney) asks Stanley to join him in the south of France to debunk a phony mystic named Sophie Baker (Emma Stone), who may or may not be taking advantage of a rich American family, he finds the offer too juicy to resist. It’s an improbable setup, to be sure, but Firth is such a convincing grouch, you get the sense that Stanley would travel just about anywhere to dash someone’s belief in life beyond the physical world.

When Stanley arrives on the Côte d’Azur, he immediately sizes up Stone as a fraud (albeit an easy-on-the-eyes one) and the Americans as nouveau-riche dupes. The family matriarch (Jacki Weaver) believes she can contact her late husband through Sophie’s séances, while her dandyish drip of a son (Hamish Linklater) is so smitten he’s asked her to marry him. The catch is, Sophie is convincing. And Stanley starts to think that maybe she’s the real deal; maybe his cynical worldview has been wrong all along. From the moment we first see Firth and Stone swap barbed insults like the leads in a Preston Sturges screwball comedy, we know exactly where Allen’s story is headed. It’s only a matter of time before the sassy sharpie and the reformed wet blanket wind up together. The director never works very hard to buck our expectations. Maybe, after 43 films, he’s earned the right not to have to. But still…

At 78, Allen seems to have decided to make only two kinds of movies: the profound and the placeholders. In the first group are deeper, more challenging films such asMatch Point and Blue Jasmine. In the second are his conceptually slight gag pictures, which have a one-joke premise and agreeably spin their wheels for a while. Moonlightfalls squarely in that second category. Its wheels spin and spin until the tires are nearly bald. B-