Significant Other is what happens when a relationship drama, a hiking trip, and an alien invasion all swipe right on each other and decide to meet in the Pacific Northwest. It’s a tight, moody little sci-fi horror film that looks like a couples’ therapy session sponsored by REI and quietly hijacked by an immortal shapeshifting entity.
Directed by Dan Berk and Robert Olsen, and starring Maika Monroe and Jake Lacy, the movie takes the classic “unresolved relationship issues in the woods” setup and chucks a meteor and an identity-stealing alien into it, just to really accelerate the emotional growth. If you’ve ever thought, “My anxiety is killing this relationship,” this movie gently responds, “Counterpoint: what if your boyfriend is actually an interstellar mimic who doesn’t understand love?”
Couples Counseling, But There’s a Meteor
We open on a red object falling from the sky, something grabs a deer with a tentacle, and the forest goes from “PNW tourism commercial” to “do not walk your dog here” in under a minute. Then we meet Ruth and Harry, who are heading into those same woods for what Harry clearly hopes is a romantic, healing getaway and Ruth clearly experiences as an ongoing emergency.
They’ve been together for six years, unmarried, and have apparently agreed they’re both fine with that. Harry, however, has been quietly nurturing the most dangerous thing in horror: expectations.
At a gorgeous scenic overlook, with water in the background and all the confidence of a man who has never watched a genre movie, Harry proposes. Ruth’s anxiety detonates. She panics, rejects him, and their shared fantasy of “chill hiking trip” dies on that spot right next to his pride.
This entire early stretch is where the film hooks you. It’s sharply written, small-scale, and painfully familiar. Maika Monroe’s Ruth is tense, thoughtful, and visibly overwhelmed. Jake Lacy’s Harry is sweet, accommodating, and just rigid enough in his optimism to be terrifying if you’ve ever been the more anxious one in a relationship. You don’t need the alien yet; the emotional horror is doing fine.
The Deer, the Cave, and the Problem of Being Too Observant
The next day, things go from “awkward silent hike” to “we should turn around” when the couple finds a deer corpse covered in black goop. Harry shrugs it off as illness. Ruth, who appears to have met movies before, is distinctly less chill. But in classic horror fashion, they don’t leave. They keep walking into the plot.
Ruth later explores a cave by herself—already a red flag—and finds a blue puddle that screams “touch me and regret it.” She also sees Harry’s dead body in a cocoon. This is the key moment: she realizes the Harry she’s been with isn’t Harry at all. He’s already been replaced.
When she emerges, she suddenly “reconsiders” his proposal and asks him to propose again at the overlook. It’s a genuinely unsettling scene because Maika Monroe plays it just a notch off, like someone cosplaying their own enthusiasm. Then, as he’s getting exactly what he thought he wanted, she shoves him off the cliff.
There’s something very darkly funny about the mechanics of that moment: the anxious girlfriend who couldn’t bring herself to say “yes” earlier now goes with “murder.” Character growth, just not the kind Harry had in mind.
The Alien Who Caught Feelings
The twist that pushes Significant Other from “solid creature feature” into “oh that’s interesting” territory is what happens next. An alien wearing Harry’s face starts roaming the woods. So far, so Invasion of the Boyfriend Snatcher. But when this Harry-impostor tries to kill Ruth, he can’t. It’s not that she fights him off physically; it’s that something in him simply won’t do it.
Turns out, when the alien copied Harry, it also absorbed his emotions—specifically his love for Ruth. Love is not a thing this alien species knows anything about. As far as it’s concerned, feelings are like a weird computer virus it picked up from licking the wrong human. And now it’s glitching.
This is both darkly hilarious and genuinely compelling. The alien is at once this cold, hyper-logical entity and also the bewildered new owner of a big messy crush. It knows Earth’s doomed; it’s here on pre-invasion scout duty. And yet, it’s standing there emotionally constipated because it cares whether Ruth is okay.
It’s like watching a Terminator suddenly discover attachment issues.
Come With Me If You Want to… Not Die Yet
In a move that’s half romantic, half horrifying, the alien-Harry decides to offer Ruth a way out: it takes her to a beach, reveals its spacecraft, and invites her to come with him to another planet before the wider invasion and destruction of Earth. It’s basically the worst possible version of, “Hey, let’s move in together.”
Ruth responds like any sensible person invited into an alien poly-apocalypse relocation plan: she stabs him.
This sequence is deliciously grim. She lures him into the water, where his blood attracts a shark. For a brief, glorious moment, it looks like nature is going to solve the problem for her. Sadly for the shark—and charmingly for the horror fan in you—the alien kills it and continues the chase. The message is clear: you can’t simply outsource your relationship problems to marine predators.
Eventually, he knocks Ruth out and cocoons her, then absorbs her traits, becoming Ruth 2.0. This is where the film pulls a very sly move: the alien copies her mind so thoroughly that it ends up saddled with Ruth’s anxiety and panic. All that overwhelm, all that fear? Now it’s his.
Watching an otherwise omnipotent shapeshifting invader get crippled by human neurosis is perversely satisfying. All the cosmic power in the universe, brought to its knees by generalized anxiety disorder.
Know Thyself (Or at Least Beat Thyself with a Rock)
Ruth escapes the cocoon—persistence is her real superpower—and faces off against her alien doppelgänger. The ensuing confrontation is simple, brutal, and oddly cathartic. She smashes its head in with a rock, which is a very primal answer to, “What do you do when your psychological baggage literally comes to kill you?”
Of course, being an immortal alien thing, its head begins to reform. There’s no permanent victory here, just a temporary reprieve. The film doesn’t over-explain the creature’s biology; it just shows you enough to make it clear this isn’t a “kill the queen and the invasion stops” narrative. The universe is bigger than Ruth’s story. She might win this round, but humanity at large? Not so much.
The End of the World, But Make It Personal
Ruth finds her way back to the parking lot—a gloriously mundane destination after all that cosmic horror—and drives off. For a moment, it feels like the classic survival ending. And then the radio speaks. The alien’s voice comes through, conversational as ever.
At the same time, red objects begin to fall from the sky, mirroring the opening shot. The invasion has begun. Whatever fragile peace Ruth might have imagined is instantly obliterated. She’s alive, she’s free, and she’s still doomed. So is everyone else.
Her emotional breakdown in the car is the logical endpoint of the film’s arc. This was never just about running from a monster; it was about a deeply anxious person realizing that the future really is as bad as she suspected, only in a completely different way than her therapist would’ve guessed.
The dark humor here is subtle but sharp: Ruth spends the entire film struggling with commitments, worst-case scenarios, and whether she can trust the person beside her. By the end, she’s absolutely right to panic. It’s just that the thing she needed to be afraid of wasn’t marriage—it was everything.
Small Movie, Big Bite
What makes Significant Other work so well is its scale. It doesn’t try to show the whole invasion, governments collapsing, or landmarks exploding. It gives you one couple, one forest, one alien, and lets the apocalypse stay just offstage until the last possible moment. The stakes are intimate first, global second.
Maika Monroe anchors the film with the same mix of fragility and steel she brought to It Follows, but here it’s channeled into something even more interior: can you live with yourself, when yourself has been weaponized against you? Jake Lacy, meanwhile, proves again that he’s unnervingly good at playing men who seem safe and aren’t—here, he’s both the earnest boyfriend and the alien echo of him, trying to understand feelings like they’re a software update.
If you like your horror with a side of relationship dread, your sci-fi with emotional weirdness, and your alien invasions starting in the least glamorous way possible (on a hike, with a deer), Significant Other is a very satisfying watch. It’s lean, mean, and just existential enough to make you look suspiciously at your partner the next time you go camping.
Not because they might be an alien. Just because they might want to propose.
