Jessie Buckley, Riz Ahmed, and Jeremy Allen White star in “Fingernails,” which introduces a test that tells you if you’re in love. Review.

What would you do if a test determined that you and your partner were completely, irrefutably, 100% in love? Would you sit back, content in the relationship you’ve already built? Or would you keep working at it? The tension between those two options lies at the heart of director Christos Nikou’s Fingernails, which stars the buzzy trio of Jessie Buckley, Riz Ahmed, and Jeremy Allen White.

Set in a future where love can be tested and quantified, Fingernails examines how total certainty in a relationship can be its own undoing. That’s a big question to consider, but unfortunately, the film doesn’t rise to the occasion to interrogate it in any particular depth. Instead, Fingernails finds itself on an all-too predictable route, albeit one that’s enjoyable enough thanks to three strong lead performances and some charming retro-futuristic sci-fi flair.

What’s Fingernails about?

Fingernails takes place in a world just like our own, except for one key difference: Couples can take a scientific test to find out if they are actually in love. The certainty of the test has caused divorce rates to plummet, but it’s also created a new tension within budding romances. How can you know if your feelings are real if a machine can just tell you whether you’re 100% or 0% in love? (Worse is the dreaded 50% result, where only one member of the couple is in love, but the test can’t tell which.)

To supposedly strengthen their relationships and ensure they pass the test, couples attend classes at the Love Institute. There, instructors guide them through a series of exercises, which range from playing competitive sports together to giving yourself an electric shock when your partner leaves the room. Nothing says love like Pavlovian conditioning!

Anna (Jessie Buckley) is a new instructor at the Love Institute. She’s joined the project to understand more about love and the ways in which the exercises help people connect further. In theory, Anna shouldn’t need to do any of this. Three years ago, she and her boyfriend Ryan (Jeremy Allen White) received a positive test; surely that’s enough to set them up for a lifetime of loving bliss, right? Wrong.

It’s clear right from the get-go that the two are stuck in a rut. Ryan, who is essentially a shrug in human form, finds peace in the routine, thinking that outside confirmation of his and Anna’s love means they don’t have to change anything about their relationship. Meanwhile, Anna wants to work on their connection every day. She tries to introduce spontaneity into their relationship in the form of modified Love Institute exercises, but she’s clearly worried about what Ryan will think, to the point that she lies to him about even working at the Institute at all.

Enter Amir (Riz Ahmed), Anna’s mentor and instructor at the Institute. He’s everything Ryan is not: devoted to the Love Institute and to bringing couples closer together. He devises several of the Institute’s most out-there experiments, including trying to fake a movie theater fire during a Hugh Grant retrospective in order to get couples to save each other’s lives. The more time he and Anna spend working together, the more she begins to sense that he’s what she’s missing in her life. But what do her newfound feelings mean for her relationship with Ryan, or for her trust in the test?

Fingernails is soft sci-fi that doesn’t go deep enough.

With its love triangle firmly in place, Fingernails sets off exploring what Anna will choose. Will she remain in the comfort of the seemingly confirmed love she has with Ryan, or risk acting on the burgeoning attraction she feels for Amir?

The path Fingernails ends up taking proves dismayingly straightforward. There’s little examination of Ryan’s complacency — he’s as good as a background character, despite White’s grounded performance. (The same goes for a highly underutilized Annie Murphy as Amir’s partner Natasha.) Meanwhile, the connection between Amir and Anna feels entirely too familiar and frankly, too underdeveloped. “Watching a love story feels safe. Being in love doesn’t,” Amir tells Anna after a screening of Notting Hill. Yet their relationship, built on lingering stares and fumbling meet-cutes, is as safe as you can get, even with all the sci-fi love testing Nikou throws at it.

The testing itself, and its implications for the wider world, do result in some of the movie’s most impactful moments. To take the love test, an instructor has to tear one of your fingernails off, meaning couples have to painfully lose part of themselves in order to know if they’re meant to be (at least by testing standards). You can instantly recognize someone who’s taken the test by the bandage wrapped around their finger, a visual shorthand that leads to some awkward questions, as more people inevitably test negative than positive. Elsewhere, details like a radio station that only plays songs dedicated to partners who break up after unsuccessful tests add further melancholy to Anna’s surroundings. After all, she’s one of the lucky ones who’s found true love — would it be wrong to give it up, given the pain the test has brought so many other couples?

The Love Institute also proves to be a fascinating environment. Headed by self-styled love expert Duncan (Luke Wilson), the Institute is rendered in twee fashion, with autumnal red walls, a soundtrack of falling rain meant to evoke romance, and whimsical maquettes laying out its upcoming exercises. The exercise sequences are Fingernails at its funniest, and sometimes its most tragic. Blindfolded sniff tests, French-language karaoke, and even skydiving are meant to heighten love and trust, but does anyone involved in the creation of these exercises really know what they’re doing? Or are they just blindly looking for love in the dark? After all, Anna and Amir can appear as lost or as desperate as their clients when it comes to love.

Take Rob and Sally (Christian Meer and Amanda Arcuri), a couple of 21-year-olds at the Institute to strengthen their bond. Anna gloms onto them almost instantly, attaching her own self-worth and romantic desires to their success. It helps that Rob resembles a younger version of Ryan; perhaps Anna sees herself in this couple, and deeply wants to recapture the beginning stages of her and Ryan’s relationship? Yet Fingernails doesn’t examine these similarities much further. Nor does it probe the biggest downside of the test — the stagnancy a positive result can provoke in couples — beyond simply acknowledging that it exists.

For their parts, Buckley and Ahmed have a charming rapport. There’s an aching sadness to both performances as well, although Fingernails doesn’t focus too hard on the root of that sadness. There’s little effort to talk through and acknowledge relationship issues after a positive test, or the loneliness negative test after negative test can provoke. Instead, the film suggests that finding a shiny new person — perhaps even projecting your own romantic ideals onto them — is the best solution to your relationship woes. It’s a frustrating approach to a genuinely interesting sci-fi concept, one that simply scratches the surface of its own potential instead of digging deeper.

Fingernails hits select theaters Oct. 27, and will stream on Apple TV+ Nov. 3.