Martin Scorsese’s pitch-black comedic expose of the obsessions of uber-fans and their effect on the objects of their affection is as odd, unnerving and painful a comedy as I could ever imagine. Robert De Niro is Rubert Pupkin, an aggressively extroverted aspiring stand-up comic and full-time autograph collector whose main attraction is to a goofy late night talk show host named Jerry Langford (Jerry Lewis). Rupert hangs out outside of Jerry’s studio after the show, watches him every night, and practices fake interviews with him and his guests (such as Liza Minnelli) in the form of cardboard cutouts on a disturbingly realistic looking homemade set in his basement dwelling (his mother, voiced by Scorsese’s own mother, can be heard yelling at him from upstairs). One night, fate (or is it a less occult force?) throws Rupert a bone and he is able to leap into Jerry’s car and accost him with his dreams and aspirations in hopes that Jerry might give him the time of day. Jerry listens politely, gives him sound if pandering advice, and has his driver drop him at home. Soon, Rupert is showing up at Jerry’s offices, calling incessantly, waiting in the lobby without an appointment, and following him from work. His partner in crime is a quirky and utterly unhinged young woman named Masha (Sandra Bernhard), whose obsession with Jerry runs at least as deep and disturbingly as Rupert’s, though it’s also tinged with a ferocious sexuality through which she finds herself unfettered. Together, they finally decide to kidnap Jerry in the hopes of coming to some sort of understanding of why he couldn’t just have been “nice” in the first place and their demands are simple – let Rupert have a guest spot on the show to showcase his shoddy routine. Rupert as a comedian is tasteless, awkward and forced, with jokes as stale as week-old bread, yet he has the audience in the palm of his hand seemingly when his penultimate achievement finally arrives. The thing about this film is that you are never sure exactly how much is real and how much is in the warped wasteland of Rupert Pupkin’s vivid imagination; early scenes feature an imagined conversation where Rupert is asked by Jerry to a nice restaurant to take over the show for six weeks while he rests, and in that fantasy Rupert’s the famous one who fans are coming over to get autographs from while Jerry is completely ignored (except by the Maitre’d). Yet later in the film, Rupert’s fantasies seem to almost spill over into the “real world” and we can’t be sure exactly if his success on the show and the subsequent fallout is true or just another wild dream somewhere in his mind. Martin Scorsese might not seem like the most obvious director for this material, and you’d be right to express surprise at the choice, yet he has actually gotten quite a bit of experience traversing the landscape of the emotionally immature and psychologically unstable (see 1976’s “Taxi Driver”). Like De Niro’s masterful portrait of Travis Bickle in that film, Rupert is a lonely, well-meaning sociopath who has such tunnel vision when it comes to his own way of dealing with the world, you’d best bend to his will or you might not make it out alive. Lewis is very funny and spot-on as the put-upon idol, and Bernhard is a revelation as the clearly insane sidekick. Then there’s Diahnne Abbott as Rita, Rupert’s lovely African-American school classmate to whom he finds himself trying to prove his current worth and success. What does she make of Rupert? Does she really believe that he will ever be what he claims he will be, or is she just along for the ride, as unconvinced and put-upon as Jerry? It’s not totally clear until the end. The film, from a screenplay by former film critic Paul D. Zimmerman, is as entertaining as a painful, bitter, wickedly awkward slog through a delusional wannabe’s existence can possibly be. Scorsese, working with cinematographer Fred Schuler (“Arthur”), doesn’t employ his usually kinetic camera, instead opting for almost realism in the simple camera movements (when there are any), and a kind of flat palette, employing colors really only in the TV offices and sets. De Niro is sort of amazing as Rupert, always forcing himself, never without a word to say, completely oblivious to the vague hints that he is simply not welcome in Jerry’s world; it’s quite a performance. As in “Taxi Driver” (1976), Scorsese and De Niro manage to find the tortured, lonely soul of a deeply disturbed individual (however relatively benign in this case that he may be), and their portrayal is fascinating, sometimes hilarious and often extremely unnerving.