“Be My Oswald” has almost nothing to do with Lee Harvey Oswald. In fact, the new film by writer-director Don Cato is a dark comedy about the plot to gun down Santa Claus during the Macy’s Thanksgiving Day Parade. (Coincidentally, “Oswald’s Ghost,” a documentary on President Kennedy’s alleged assassin, also opens this week.)

The main character, known simply as A (Jeannie Noth), is a well-heeled, sheltered woman who broke off her engagement and ran away to find her purpose in life — and find a job. Hoping to make a difference in the world, she answers a newspaper ad placed by a chain-smoking, vegetarian revolutionary known as — wait for it — B (Katha Cato, the director’s wife). With a stuffed kitten named Muffy tucked in her Prada handbag, A embarks on her first mission, which is to secure office space with a Broadway view. The task proves daunting, and A soldiers from one roach-infested dig to the next. Before long, she breaks down and rushes off to a salon to get her hair done. She has no idea of the challenges ahead, which will include a creepy neighbor (Buddy Smith), a nosy caterer (Maggie Maes), a couple of thugs, and B’s emerging plan to rid the world of holiday consumerism.

Although this holiday movie is definitely more naughty than nice, it doesn’t stoop to the lowest common denominator like the expletive-laden “Bad Santa.” “Be My Oswald” is a deadpan satire that unexpectedly unfolds like a chamber piece — think the Branagh-Pinter “Sleuth,” only with more fun and suspense. The “Sleuth” comparison is apt, since both are essentially two-character plays with murderous intrigue. But unlike the battle of wits in “Sleuth,” in “Oswald” our heroine’s gullibility makes her no match for B. Perhaps that’s part of the charm of Mr. Cato’s film, since the power shift and struggle come as totally unexpected and genuine. The film even manages to pull off a homoerotic tangent, a feat at which “Sleuth” tried and failed.

The supporting cast seems uniformly amateur and over-the-top, but Ms. Noth and Ms. Cato’s performances are captivating. Were it not for Mr. Cato’s deft direction, one could easily forget that the bulk of the film actually takes place within the claustrophobic confines of one dilapidated room. Truly independent features are generally a mixed bag, but “Be My Oswald” is one that stands out. It’s as slick and well-made as any test-screened indiewood flick, but it doesn’t have a major distributor, perhaps because no one knows how to sell a film such as this one. Those in search of belly laughs are definitely in for a disappointment, but “Be My Oswald” is just about the zaniest chamber piece in recent memory.