Like its title character, “Hello, My Name is Doris” is alternately sweet and kind of creepy, a seriocomic tale of a spinster who’s also a hoarder—and becomes a supposedly sympathetic stalker. It’s also a star vehicle for Sally Field, who certainly inhabits the character with conviction without ever making you feel that Doris is real rather than a literary construct.

Doris Miller is an unmarried Staten Island woman in her sixties. Her mother, with whom she shared a crowded house all her life, has recently died. Her closest friend is a voluble widow, Roz (Tyne Daly), with whom she works out, and whom she accompanies to self-help lectures like one delivered by Willy Williams (Peter Gallagher), a smooth speaker who encourages her to take some risks and expand her horizons.

The socially awkward Doris works in a cubicle at a Manhattan office, where she’s a leftover from a previous regime, dutifully entering data into the firm’s records and being treated with condescension by her much younger colleagues. But when John Fremont (Max Greenfield), the new design executive, arrives from California and treats her relatively kindly, Doris is immediately taken with him as a possible romantic interest, despite the age difference. To connect she enlists the aid of Roz’s teen granddaughter (Isabella Acres) to set up a fake social media account that will allow her access to his likes and dislikes. Discovering his interest in an electronic band, she dresses up in colorful garb and goes to one of their concerts, where she naturally runs into him. Matters take a turn that strains one’s ability to suspend disbelief even further than the picture already has, when the band enlists Doris to model for the cover of their next album. She believes that John is seriously interested in her.

That’s why she’s so distressed when she finds John with Brooklyn (Beth Behrs), a pleasant young woman whom he identifies as his girlfriend. She even befriends Doris. But using that phony web account, Doris sabotages the relationship, believing that will force John to turn to her. It doesn’t work, of course, and leads to an embarrassing admission. At the same time Doris’ brother Todd (Stephen Root) and his wife Cynthia (Wendi McLendon-Covey) decide to intervene at home, enlisting a therapist to assist Doris to break her hoarding drive so that they can clear out her house and sell it. Obviously her life is about to change radically in a variety of ways.

There’s no doubt that writer-director Michael Showalter, working from a short film by his co-scribe Laura Terruso, is aiming for a quirky mixture of humor and pathos, and there are moments when he partially hits the mark. The sequence in which Todd and Cynthia burst into Doris’ house with the therapist in tow, forcing her to comply with their plans or resist, is actually quite affecting, and Field plays it for all its worth. She’s also excellent in a poignant confession when she reveals that she once had a boyfriend, but gave him up to stay with her mother.

Otherwise, however, Showalter doesn’t manage the tonal changes very skillfully, and Field is unable to compensate. Doris sometimes seems charmingly oddball, but at others she comes across as seriously deluded, and a viewer might well be tempted to think her behavior more disturbing than mildly off-kilter. You might find yourself laughing at her as if she were a joke at one moment, pitying her because of her desperation the next, and cringing over her inappropriate behavior a second later. Ideally these transitions would be smooth, but here they’re jarring, and the effect is just unsettling. Even Field seems uncertain what she’s going for at some points.

Still, like so many actresses her age, Field doesn’t get many opportunities to shine, and it’s good to encounter her in a starring role, even when the vehicle is such an imperfect one. She finds a likable partner in Greenfield. John might easily have been played as some sort of simpleton, but he manages to avoid that. Root is underused as Todd, but Daly is a hoot as Roz. On the technical side Melanie Jones’s production design (especially in Doris’ house and cubicle) and Rebecca Greggs’s costumes for Field deserve notice, but like Showalter’s directorial touch, Brian Burgoyne’s cinematography is simply functional.

Sally Field remains a trouper, but “Hello, My Name is Doris” is an invitation you might want to skip.