Logan Lerman as Isaac, left, and Molly Gordon as Iris in "Oh, Hi!"

We've all seen movies that have a great premise and a solid story, but they fail in execution, because the filmmakers just can't bring it off. The reverse situation is almost never heard of - a movie with a bad premise and weak story that, somehow, kind of works.

But "Oh, Hi!" is that rare case, a movie that's engaging and interesting moment by moment, but everything else is wrong with it. Writer-director Sophie Brooks locks into a narrative that's unpleasant and far-fetched and that forces the characters to behave in ways that make no sense. And Brooks concludes the movie as if in search of the least dramatic ending she could devise.

What holds it all together is Molly Gordon, who stars in the film and co-wrote the story with Brooks. She plays a young woman, Iris, who goes away for the weekend with her boyfriend, Isaac (Logan Lerman). They have been dating for four months, and this weekend represents a milestone – their first time away together and an opportunity to get closer.

Logan Lerman as Isaac, left, and Molly Gordon as Iris in ‘Oh, Hi!' (Sony Pictures Classics)

The first 20 minutes of "Oh, Hi!" are the best, which is odd, because next to nothing happens. The movie begins with them driving down the road, stopping to buy strawberries. Then they get to the house that they're renting, have sex, go swimming, and have sex again. At this stage, the movie provides nothing but the pleasant spectacle of two people getting along.

Yet if you pay close attention, you might detect some points of potential conflict. Very subtly, Brooks and her actors are able to hint that, while Iris is wholeheartedly keen on Isaac, Isaac may have some reservations about Iris. Though he can be effusive and demonstrative, he can also be, at times, guarded, as if reserving judgment or concealing his thoughts.

Logan Lerman as Isaac, left, and Molly Gordon as Iris in "Oh, Hi!" (Sony Pictures Classics)

This comes to a head when, at the worst possible time, he tells Iris that he is seeing other women and doesn't want to be in an exclusive relationship. Her reaction is extreme - don't read any other reviews if you don't want to know how extreme - and the rest of the movie is about the consequences of that response.

The film hinges on Gordon's ability, not to be sympathetic, but engaging and fun to watch. Over the years, I've noticed that the best emerging stars are often people who already seem familiar the first time you see them. Gordon is like that - familiar, while also being likable, refreshingly self-mocking and comedically inventive.

Easily, the character of Iris could have been played as a flat-out wackjob, and the film could have descended into horror-movie territory, but Gordon, without softening Iris' bizarre behavior, sets a light tone.

John Reynolds as Kenny, left, and Geraldine Viswanathan as Max in ‘Oh, Hi!' (Sony Pictures Classics)

In the end, "Oh, Hi!" can almost seem like a meaningless exercise, because the points Brooks seems to be making - about the difficulties of establishing intimacy and the obstacles in the way of commitment - are fairly banal. That these difficulties are especially pronounced for millennials and Generation Z folks helps Brooks somewhat, but the movie glances off these issues in such a superficial way that it's hard to feel that anything important is being said.

Yet sometimes things are best said without words. There's something about the way in which Gordon plays Iris - with her insecurity and neediness living alongside her wit, good humor, vivacity and intelligence - that speaks louder than the screenplay. Gordon makes you think, wow, if someone of such obvious appeal is coming unglued, maybe times are tough all over.

Mick LaSalle is the film critic emeritus of the Chronicle. Email: [email protected]

More Information

"Oh, Hi": Romantic comedy. Starring Molly Gordon and Logan Lerman. Directed by Sophie Brooks. (R. 94 minutes.) In theaters Friday, July 25.