I’m too trusting to make documentaries. But I’d like to think I’d see a red flag if the subject of my hypothetical documentary was dying of heart disease yet started smoking meth for the camera. I’d talk to a doctor — maybe his. But just before the dying illusionist-comedian John Szeles inhales in “ The Amazing Johnathan Documentary ,” the director, Ben Berman, freezes the image, drains it of color and then uses audio of Szeles reconsidering the wisdom of allowing anybody to see him doing this. Nothing in this movie is wise. It’s reckless and indulgent, which could really work for the story of a middle-aged sleight-of-hand entertainer who’s cheating death.

But it becomes clear — probably in the meth moment — that Berman’s in over his head. It’s also clear quite soon that Szeles, who performs as the Amazing Johnathan, is up to something cruel and self-serving but, for the purposes of our absorption, clever, too. The movie has a plot twist, in other words. In fact, it’s got about four. I won’t get into any of them except to note that Berman can’t quite juggle it all. He’s confused, which seems fair (this is his first full-length film). But he hasn’t shaped that confusion into a movie worthy of the game being played with him. He turns it into a movie about himself. That’s when the water rises to his scalp.

This thing was probably meant as a sentimental chronicle of both Szeles’s return to magic and his medical miracle — he says he was told he had just a year to live; the movie finds him three years later, in 2017. It starts with a montage that relives Szeles’s career peak, in the 1990s, when he wore a sweatband over his longish, blondish hair. (He looked less like a magician and more like a joke on the celebrity-fitness-guru craze.) Comedians appear in order to make the standard talking-head observations, although, in the early going, some of what they offer about Szeles is pretty stale. (“He has nothing to lose,” says Penn Jillette; “He’s a disrupter,” says Judy Gold.) Szeles’s wife, Anastasia Synn, is here, full of spice, enablement and worry.

But when the first twist came, I applauded. It’s funny! Actually, they’re all funny. Like, in a Charlie Kaufman, “Adaptation” sort of way. Like, maybe the whole movie’s a stunt. And yet that ambiguity neither makes Berman Spike Jonze nor turns him into an illuminating investigative reporter. Each new wrinkle is a personal affront that leads him to a state of only moderately productive self-reflection. And even that’s an inorganic impulse, inspired by conversations with his buddies.