Like the unreliable-narrator novel, the unreliable-perspective movie is a tricky proposition that can be fascinating, but requires considerable finesse. The auspicious central conceit of “Aardvark,” Brian Shoaf’s first feature as writer-director, features Zachary Quinto as a mentally ill man whose difficulty separating reality from delusion is shared with the viewer. But the film can never quite decide what it wants to be — wounded-inner-child drama, quirky comedy, quasi-thriller, all the above — and its good ideas never quite gel, or lead toward sufficient narrative revelation. Though supporting roles for Jon Hamm and Jenny Slate will help spark some interest, this offbeat but low-pulse effort ultimately lands in a dissatisfying zone between the intriguing and the turgid.

Given the careless floppy hair and doughy look of someone who’s been zoned out on psychopharmaceuticals for a long time, Josh Norman (Quinto) lives a marginal existence in upstate New York. His apartment is a recluse’s dump, his parents are deceased, he appears to have no friends, and getting a job at a local cafe is a big step he’s probably not really up to handling. But the issue that has him re-entering therapy is the knowledge that estranged older brother Craig (Hamm), a semi-famous actor, is back in town after several years’ absence.

Therapist Emily (Slate) finds Josh withdrawn, defensive, awkwardly jokey and evasive on such key matters as his clinical diagnosis, medications and precise issues with regard to the prodigal Craig. Josh claims he’s already seen his brother — but that’s misleading; what he really means is that in his paranoid imagination he increasingly believes Craig is disguising himself as everyone from a bag lady to a cop in order to mess with little bro’s head. Offering some solace from these disorienting encounters is Josh’s tentative relationship with a sympathetic young woman (Sheila Vand, from “A Girl Walks Home Alone at Night”) who seemingly materializes out of nowhere to offer companionship.

Meanwhile, Emily — who appears to be the kind of mental health professional who could use help in that department herself — is approached independently by the real Craig. In town to sell their late parents’ house, he’s concerned about his brother but reluctant to approach him. He’s also a charmer, and it doesn’t take long for him and this wobbly therapist to ignore all obvious conflict-of-interest red flags and fall into bed together.

Though technically polished, “Aardvark” lacks the assertive directorial style that might have papered over its sketchier elements, which in the end feel more underdeveloped than usefully ambiguous. Hamm finds little character or motivational specificity in Craig; some brief childhood flashbacks and a climatic face-to-face between the brothers reveal too little about their troubled relationship. Vand is stuck playing a (deliberate) cipher. Slate is restrained here, but still too inherently comedic a presence: She seems to exist in a separate neurotic romantic-comedy universe under-supported by the screenplay. (It’s typical that when Emily visits a psychiatric mentor, played by Stephen Schnetzer, for professional advice, we get no insight as to what mutual history makes him so hostile toward her.)

Quinto, also a producer here, gives a conscientious performance. But Josh’s distorted viewpoint is (nearly) the whole movie — and Shoaf doesn’t seem concerned that we never fully grasp where he’s coming from, let alone what made him that way. It’s not even clear why the film is called “Aardvark,” or why it begins and ends with footage of that mammal in captivity.

The film might have worked better as a stage play — Shoaf trained as a playwright — in which actors multi-cast to convey Josh’s hallucination-prone perception perhaps could have proved vivid enough to compensate for the story’s vagueness. In the film’s relatively naturalistic presentation, too much suspension of disbelief is required without justification — all the way down to an ending that’s too simple and sunny to make much sense for these characters.

Though attractive on its own, Heather McIntosh’s string-quartet score tends to underline the movie’s somewhat self-conscious, borderline-ponderous tenor. There are several; well-chosen songs soundtracked, however, by the likes of Numero Group and Andrew Bird. Eric Lin’s cinematography and other major contributions are fine, but “Aardvark” needed a bolder stylistic approach, a more insightfully detailed screenplay, or both, to make the most of a promising premise that never really develops.

Film Review: ‘Aardvark’

Reviewed online, San Francisco, March 4, 2018. (MPAA rating: PG-13.) Running time: 89 MIN.

  • Production: A Great Point Media release of a Great Point Media presentation in association with Slendro Media of a Before the Door/Susie Q production. Producers: Neal Dodson, Susan Leber, Zachary Quinto. Executive producers: Robert Halmi Jr., Corey Moosa, Jim Reeve, Brian Shoaf. Co-producer, Joyce Pierpoline.
  • Crew: Director-writer: Brian Shoaf. Camera (color, widescreen, HD): Eric Lin. Editor: Marc Vives. Music: Heather McIntosh.
  • With: Zachary Quinto, Jenny Slate, Sheila Vand, Jon Hamm , Dale Soules, Peter Grosz, Stephen Schnetzer, Tonya Pinkins, Marin Ireland, Jacinto Taras Riddick, Noah Robins, Alex Kramer, Michael Oberholtzer
  • Music By: