There is an irony when Danny DeVito utters the opening lines of “Duplex,” as the film really isn’t in his voice. This is only DeVito’s third venture as a director into the world of dark comedy, but with “The War of the Roses” and “Death to Smoochy” on his resume his name evokes expectations of brilliantly dark, stinging humor. Yet other than a few shining moments, “Duplex” relies entirely upon juvenile sight gags to generate jokes that really aren’t all that amusing.

Alex (Ben Stiller, “Zoolander”) and Nancy (Drew Barrymore, “E.T.”), a young happily-married couple, buy their first house ? a darling duplex in Brooklyn with plentiful space and charming character ? only to discover that their upstairs tenant, Mrs. Connely (Eileen Essel, “The Canterbury Tales”), is not the sweet old woman they expected but rather a nagging, possibly malicious hag who slowly ruins their lives. Rent control laws prohibit them from evicting the tenant, so the young couple, after much ado, decides to kill her.

The premise of two young urban professionals trying to perform wet work is sufficiently ripe with darkened comic potential to carry a film, but “Duplex” shows too much restraint, shying away from fully exploiting the idea. The film’s finest moment comes when Alex walks down a shady alley in search of black market guns, creating an uproarious cultural juxtaposition. Beyond that isolated moment of glory, the film refrains from dark, witty, situational humor like Oliver Rose’s pissing on the fish in “War of the Roses” or Rainbow Randolph’s baking of phallic cookies in “Death to Smoochy.”

Rather, the picture’s comedy ? or lack thereof ? is derived from simplistic, tired elderly jokes centering on Mrs. Connely’s age. Seeing the hag’s wrinkles exposed in a bathtub is the sort of witless shock value which “Duplex” is all too full of.

The plot also suffers from a critical false tension. In fact, New York City landlords do have a right to evict rent control tenants, so long as they plan on occupying the space themselves, something that Alex and Nancy explicitly desire.

That is not the film’s only realistic fault, however. “Duplex” comes with a twist ending ? which is fully unnecessary as the plot requires no such convolution ? full of impossibilities. The surprises employed would require no small degree of clairvoyance on the part of several characters and numerous acts of God.

Then again, reality obviously wasn’t much of a concern, given that one scene shows Mrs. Connely paying her $88 rent in exact change ? with a $100 bill.

Acting-wise, Stiller is shamefully one-note in the movie. Further, the young actor might consider taking stock of his career before he becomes typecast as the slapstick always-out-of-luck character he played in “There’s Something About Mary,” “Zoolander,” “Meet the Parents” and assorted other films.

The rest of the cast is as mediocre as the film itself, with the shining exception of Harvey Fierstein who brings rare moments of light to the screen in his small role as a real estate agent. Mixing the charm of his Edna Turnblad from Broadway’s “Hairspray” and the cunning of his Merv Green from “Death to Smoochy,” the actor molds a complexly enjoyable character that always steals the scene.

As a whole, just how shameful is “Duplex?” Consider this, as of Sunday, Miramax, the film’s distributor, had removed all links to the film’s website from it’s corporate homepage, and if one does manage to stumble onto the movie’s Internet hub, they will be dually assured that it will be “In Theater” in “October 2003.”

Yes, “Duplex” is such a catastrophe that even it’s distributor appears to have given up all hope.

Grade: D