Want to see Jennifer Lawrence haggle over industrial parts? This is the movie for you! Otherwise …

Jennifer Lawrence in Joy.

Courtesy of 2015 Twentieth Century Fox Film Corporation

David O. Russell’s Joy, a shambolic biopic of real-life homemaker-turned-businesswoman Joy Mangano, is an unabashed valentine to Jennifer Lawrence, who served as the volatile director’s muse in his last three sprawling ensemble comedies (and who won a best actress Oscar in 2012 for the strongest film of the trio, Silver Linings Playbook). But not every filmmaker-to-actor valentine, heartfelt though it may be, is something the outside world needs to see. Joy contains moments of delight, humor, inspiration, and heartbreak—many of its individual scenes, cut loose of their context, could stand alone as successful mini-movies. But Russell’s method of barely controlled chaos—his tendency to keep subplots boiling on multiple burners as he rushes from one seriocomic setup to the next—doesn’t serve the final product well in this case. Joy, which was co-written by Russell and Bridesmaids scribe Annie Mumolo, went through four editors in the course of post-production, and the seams show in the form of shifts to the film’s pacing and tone that feel too abrupt and jarring to be deliberate.

For the first 20 minutes of its running time, Joy appears to be a dysfunctional-family comedy à la Silver Linings Playbook, with Robert De Niro once again in the role of well-meaning but hapless paterfamilias. As Rudy Mangano, he runs a semi-successful car-repair business, managed by his older daughter, the officious Peggy (Elisabeth Rohm). But it’s Peggy’s put-upon half-sister Joy (Lawrence), an unemployed and divorced mother, who holds this barely solvent and even less sane family together. Joy’s mother (an almost unrecognizable Virginia Madsen), long since divorced from Rudy, spends her days in bed watching soap operas (affectionately pastiched by Russell using such daytime-TV legends as Susan Lucci and Laura Wright). Joy’s ex-husband and the father of her children, a charming but perpetually broke Venezuelan musician (Edgar Ramirez), is currently crashing in the family basement. When De Niro’s Rudy is thrown out of the house by his current wife, he takes up residence in the same basement as his former son-in-law, making for a full, loud and argumentative household.

It isn’t long before Rudy, who can’t stand to be alone, meets a new lady friend through an online dating site. Trudy (Isabella Rossellini, giving a very funny performance as a would-be grande dame) is a well-off widow given to speaking in lugubrious tones of her dearly departed husband, Morris. During an awkward family outing on Morris’ swanky yacht, Joy finds herself tasked with a particularly nasty cleanup job, swabbing the deck after a spill involving red wine and broken glass.

And with that scene, Joy swerves unexpectedly into a completely different narrative zone. No longer a freewheeling comedy about a nutty extended family, it becomes, for its middle section at least, a single-minded portrait of one woman and her mop. The not-yet-existent mop of her dreams, that is: After slicing her hands on glass shards in that unfortunate deck-swabbing incident, Joy, who since childhood has dreamed of becoming an inventor, becomes obsessed with the idea of designing a more convenient floor-cleaning tool. What if a mop could be wrung dry without having to reach down and touch the disgusting mop-head itself? What if said disgusting mop-head could be easily removed, thrown in the wash, and reattached, ready to clean anew?

If you own a mop that performs these functions—a Miracle Mop, as it was originally known when it was introduced in the early ’90s—you have the real-life Ms. Mangano to thank for your gunk-free hands. But Joy’s path to entrepreneurial success wasn’t easy, as Russell spends the second act of the film somewhat laboriously demonstrating. Based on a series of sketches made with her daughter’s crayons, Joy convinces a skeptical Trudy to sponsor her first run of custom-manufactured mops. But no store is willing to take a chance on this unfamiliar new product, which, at $19.95, is priced higher than any other mop on the market. It isn’t until Joy is introduced to the QVC executive Neil Walker (Bradley Cooper) that her fortunes begin to turn.

We’ve seen Cooper and Lawrence strike sparks off each other before in a David O. Russell joint—Silver Linings Playbook, where they played a pair of mentally unstable but curiously meant-for-each-other lovers. Here, their characters’ connection is professional rather than romantic, but the energy that flows between them is just as crackling. With the appearance of Cooper about two-thirds of the way in, Joy becomes yet a third kind of movie—neither a screwball family comedy nor a portrait of the artist as monomaniacal entrepreneur, but the story of a business partnership made in heaven. After her first attempt to peddle her invention on the shopping channel ends in disaster, Joy, on the brink of filing for bankruptcy, decides to strong-arm the practical-minded Neil into giving her one more shot. In a scene that’s one of the film’s highlights, Joy overcomes her terror of appearing on live TV and, addressing the audience as the regular-gal homemaker she is, proudly demonstrates the various convenient features of her humble invention. The connection is made, the QVC phones start ringing, and a housewares empire is born—but not until after more plot complications involving patent fraud, dishonest parts manufacturers, and passive-aggressive attempts at sabotage by members of Joy’s family.

If, like Russell, you’re a big enough J-Law fan to enjoy the spectacle of this smart, charismatic performer doing pretty much anything—including fixing plumbing, haggling over the pricing of plastic injection molds, or wringing out a grubby pre-Miracle mop with bare, bleeding hands—Joy may bring you the joy its director seems intent on delivering. But as likeable as its enterprising heroine may be (and as well-supported as Lawrence is by a plethora of fine performances, including Diane Ladd as Joy’s forbearing grandmother and Dascha Polanco as her unsinkably optimistic best friend), Joy the movie never cohered, for me, into a story with forward motion. The minute the film begins to find its footing in one tonal register, it switches to another, and none of the most interesting relationships—particularly Joy’s push-and-pull power games with Cooper’s smooth corporate exec—are allowed enough onscreen time to be satisfyingly explored. The film’s final image of Joy, striding triumphantly down the street after besting a sneaky corporate rival, invites the viewer to share a sense of closure that doesn’t feel earned by the wildly scattered movie we’ve just watched. Dare I end a review of a movie about innovations in mop technology with the observation that Russell hasn’t wrung his heroine’s story for everything it has to offer?