It's right there in the trailer: cake and cancer.

Less obvious in the same trailer for the new Amazon Prime Video feature "Sitting in Bars with Cake" is that there's considerable effectiveness and genuine feeling found in Audrey Shulman's adaptation of her 2015 book of how she baked her way through a full year of "cakebarring," with the express intention of meeting guys in Los Angeles.

Shulman's best friend, meantime, received a devastating health diagnosis, but at her urging Shulman soldiered on with her project.

In a freely invented variation on that premise, "Sitting in Bars with Cake" creates a story, from ingredients that won't strike anyone as radically fresh. But it's moving story of a friendship brought to life by Minneapolis-born Yara Shahidi and Odessa A'zion.

Shahidi's character, Jane, starts out as a tightly wired, socially anxious woman in her early 20s, trying to live up to her parents' expectations of greatness. Corinne, her longtime friend and fellow Phoenix-to-L.A. transplant, is nothing like Jane; she's a wisenheimer and a blithe extrovert played by A'zion, best known for the Netflix series "Grand Army" and the recent "Hellraiser" reboot.

The friends work at the same company — Jane as a mail clerk with uncertain designs on a law career, Corinne as an enterprising music agent in training. (Bette Midler, always a pleasure, plays her imperious but warmhearted boss.) For Jane, baking is her preferred anti-stress self-medication. One night, lugging a beautiful cake for Corinne's birthday, Jane impresses a bar full of semi-eligibles with her baking prowess.

So why not get busy with it? With Corinne's nudge, Jane embarks on a yearlong experiment in a carefully mapped array of bars.

Shulman, now a screenwriter, happens to be a good one: She's quippy and frequently funny, and knows how to change gears without too much strain. Director Trish Sie ("Pitch Perfect 3″) is no stranger to commercial engineering, but her work here leaves room for some easygoing interplay, in more than one key. Even after Corinne's cancer diagnosis, the movie proceeds as a series of shameless L.A. tourism campaign spots. Ordinarily, that slickness would be enough to stop a film like this cold. This one's different, and better.

The stars, and the key supporting ringers, come in extremely handily. Shahidi (a young veteran of both "Black-ish" and "Grown-ish" and whose father worked as Prince's personal photographer) avoids turning Jane into a type, or a mere introvert-to-butterfly cliche. Her vibe is relaxed and intuitive enough to sell whatever's up with Shulman's week-by-week, cake-by-cake setups. Same with A'zion.

Corinne's parents, salt of the earth but slightly off in the best way, give Ron "Mr. Reliable" Livingston and Martha Kelly ("Marriage Story") a lovely double act. The movie tells the story of "a year spent in hospitals and bars," and it's laid out as such, in a spoken line of dialogue. As Jane devotes all the time and love she can to Corinne, while the doctors monitor the brain tumor and its effects, screenwriter Shulman has the grace to allow Corinne a clear-eyed set of complicated responses.

"I should be learning some major life lesson right now," she says at one point, in an unguarded moment with her friend and intrepid baker. "But I'm just annoyed."

The scenes between A'zion and Shahidi aren't the icing on this cake. They're the cake.

'Sitting in Bars with Cake'
3 stars out of 4
Rated: PG-13 for language, some drug use and sexual references)
Where: On Amazon