Leslie Mann, Nicki Minaj, Cameron Diaz and Kate Upton in The Other Woman.

Leslie Mann is one of my favorite comic actresses, and I’ve been waiting for her to get a project that would put her over the top as one of Hollywood’s go-to actresses. I thought This Is 40 would do the trick, but I was probably the only guy in the world who thought that was a good movie.

Now comes The Other Woman, a film that casts her as a wimpy victim of her cheating husband, Mark (Nikolaj Coster-Waldau). She winds up befriending Carly, his mistress (Cameron Diaz), and she becomes a stronger, independent person as the film progresses.

Whatever.

Director Nick Cassavetes is trying for a straight comedy here, and things work well enough for at least half of the movie. Mann is at her pathetic best while stalking Diaz’s character, crying on her doorstep with Boston Market food in hand as a peace offering, and a big Great Dane in tow. I enjoyed this film in its early stages, thinking it might be the showcase Mann deserved.

Then The Other Woman crashed into a creative wall. I’m not sure about the precise moment when the film goes off the rails. Maybe it’s when yet another mistress, played by Kate Upton, enters the film, and the women start working together to torture and destroy the cheater. Mind you, I am all for a movie in which a cheater gets his comeuppance—just not when one of the revenge-seekers is played by the beautiful but bland Kate Upton.

Or maybe it’s the moment when Carly pours a bunch of laxative into Mark’s drink at dinner, and he proceeds to not only crap his pants, but have a bathroom-stall catastrophe similar to the one Jeff Daniels suffered through in Dumb and Dumber. Daniels made his fecal apocalypse high art. Coster-Waldau makes his feel like plagiarism.

Cassavetes has made some good movies in the past, including She’s So Lovely, with Penn and Travolta, and The Notebook, which gets credit for devastating movie viewers all over the world. The Notebook and, to a lesser extent, My Sister’s Keeper (also with Diaz) show Cassavetes’ talent for making people weep. However, The Other Woman shows that he can also make moviegoers groan. Tonally, the film is all over the place, as if he set out to make a raunchy comedy, and then decided to retreat into PG-13 territory. Indeed, I caught a major moment in which Diaz is clearly over-dubbed while screaming the big f-word. Maybe Cassavetes set out to make a much uglier film, and the studio stepped in and said, “Clean it up!”

By the time near the film’s end when Coster-Waldau’s character smashed his nose, and blood was squirting out of his face, it had ceased being funny and had become a total mess. Not even the mighty Mann’s expert mugging could pull it out of the fire.

The Other Woman was a minor hit at the box office during its opening weekend, so maybe its success will get some decent scripts in front of the talented Mann. It’s hard to watch her in this sort of squalor.

The Other Woman is playing at theaters across the valley.