In “She Came to Me,”Peter Dinklageplays an opera composer with a creative block, andMarisa Tomeiplays a tugboat captain who jolts him out of his rut by seducing him and complicating his life.

If you’ve seen the trailer for the movie, you already know all this. What you probably don’t know is that the trailer contains almost everything that’s interesting, clever or alluring about an otherwise jumbled and trite attempt at romantic comedy.

Written and directed by Rebecca Miller (“Maggie’s Plan”), “She Came to Me” seems to have been constructed around the nugget of a wonderful idea. Several wonderful ideas, actually.

Just at the level of an elevator pitch, the composer-captain romance is gold. It puts a spotlight on characters who don’t usually show up onscreen to fall in love — certainly not amid the conventions of the bourgeois-artsy Brooklyn rom-com — and asks us to reconsider our attitudes toward work.

该元素肌萎缩性侧索硬化症o allows Miller to be interestingly canny about the nature of artistic inspiration. In the film’s single most glorious moment, we witness Dinklage’s character suddenly turn the experience of an afternoon quickie into the basis for an opera.

For that matter, anything in “She Came to Me” that has to do with either opera or tugboating is a delight. We see excerpts from two of the Dinklage character’s creations, with music by composerBryce Dessnerthat justifies the notion that these operas would be successful. There are even cameo appearances by a handful of top-tier opera singers, including countertenorAnthony Roth Costanzoand mezzo-sopranoIsabel Leonard. A rehearsal scene provides a hilarious close-up of a creative artist unable to keep his desire for control in check.

When Miller brings us aboard the tugboat, she’s an affable tour guide. Tomei’s character is voluble and engaging about how her trade operates, and the camera plunges us into the vessel’s homey, claustrophobic interior.

And although Miller has neglected to provide much in the way of an interior life for either figure, the lead actors come to her rescue with performances of eloquent specificity.

Dinklage, with his hangdog eyes buried beneath a shaggy mop of hair and a beard that seems to be growing down his neck and into his shoulders, is a man in hiding — ashamed of his failures, terrified of being called to account. Tomei, by contrast, is wide open and weather-beaten, with a frankness that pulls the drama forward.

If only that were the entire movie, “She Came to Me” would be a small-scale gem. Unfortunately, that sliver of plot is surrounded by miscalculations and cliches on every side.

As Dinklage’s germophobic therapist wife, Anne Hathaway is on hand to provide a caricature of the kind of performance that people who hate Anne Hathaway performances hate — brittle, mannered, skin-deep. A pair of sexy high-school geniuses cope predictably with the trials of young love, a pasteboard villain of a stepfather drags people to his Civil War reenactment, an order of nuns dispenses charity, and many brownstone interiors are lovingly documented.

米勒把不同的线程在end in a rush, like a college student dashing off the final pages of a term paper in the wee hours. But until then, she hops from one plotline to another, leaving the audience scratching their heads and waiting for another visit to the opera house.

Reach Joshua Kosman:jkosman@sfchronicle.com