Nothing puts more stress on a young marriage than a pesky demon. Such is the problem that Lou (Cher Álvarez) and James (Travis A.Knight) face in Paranormal Activity, the chilling stage adaptation from the hugely successful Blumhouse horror franchise, that is currently playing at the Emerson Colonial Theatre through July 30 before heading to Broadway. This production, which has been a hit in London, previously ran in Chicago, Los Angeles, and San Francisco late last year.

What playwright Levi Holloway and director Felix Barrett have done is take the franchise’s title and the idea that there are malevolent spirits out there and spin it in a different direction. Unlike the series, they are not captured through technological means—no video footage of these things that go bump in the night, which is a hallmark of the franchise. Instead, they create a contemporary take on an old-fashioned ghost story but with one very clever twist: ghosts aren’t tied to a location; they are attached to a person. It isn’t the house that’s haunted; it is you.

In the play, Lou has spent the previous year under great emotional stress for two reasons: the first being she believes she is being haunted and that no one, including her new husband James, believes her. When the opportunity comes for James to relocate to London for his job, he takes it with hopes the new surroundings will improve things. But as they settle into their new home, cleverly visualized in Fly Davis’s two-story set of a comfortable modern home, Lou begins to feel a ghostly vibe is present. Making matters worse is James’ mother Carolanne (Shannon Cochran, seen on a large-screen television in video calls). She is a smothering Bible thumper whose intent is to make her son believe Lou is psychotic. Played with saccharine perfection by Cochran, her sunny demeanor barely hides her true intentions – bullying her son to get his wife pregnant so she can be a grandmother. James’ unusually close relationship with her is one red flag that Lou missed during their courtship, where she was seduced by his humor and good looks. But it isn’t just Carolanne pressuring Lou — James has designated a room in the house as a nursery, much to Lou’s chagrin.

Lou has an unusual interest in the paranormal, spending hours listening to podcasts by Etheline Cotgrave (Eva Kaminksy), a renowned British medium who expresses her belief that “places aren’t haunted, people are,” which Lou has come to believe but James scoffs at. He agrees with his mom that her issues are psychological, and when she has a brush with a spirit, he asks if she’s been taking her meds. It takes a truly frightening event to convince him otherwise.

That happens midway through the first act thanks to the extraordinary stage wizardry of Chris Fisher, whose split-second illusions are like those in a nightmare. (He also designed the eerie effects for the American Repertory Theater’s recent Black Swan.) Fisher’s work is only one component in the stagecraft that slowly engulfs the audience with a sense of dread. Davis’s sprawling set fills the Emerson Colonial stage with a cutaway of a duplex home with a vast living room/kitchen on the bottom level and three rooms above, including a bathroom in which James casually takes a leak in full view of the audience. (Is that a first for a Boston stage?) As the lights go out, which they often do, the space becomes ominous, and your eyes sense movement in the darkness. Is there something on the stair or behind the shower curtain, or are your eyes playing tricks? Anna Watson’s brilliant lighting design has something to do with creating the shadows where these spectral occurrences may be happening. There is also the sense of the world outside seen in random headlights of cars zooming by that catch the attentive audience off-guard. Add Gareth Fry’s sound design filled with jarring blasts of Nirvana and creepy ambient underscoring for a perfect storm of horror elements. Even the doorbell rings ominously.

And when it rings, expect great suspense as James goes to answer it, thanks to Barrett’s taut direction. While the effects scare, it is the slow building of tension, both in the occult happenings and in the couple’s relationship, that makes Paranormal Activity work so well. Barrett is the artistic director of Punchdrunk, the immersive theater company whose Sleep No More turned a Brookline school into a haunted house some 17 years ago under the auspices of the ART. What was most memorable about that take on Macbeth (that moved the story from room to room) was just how effectively creepy it was. Who could ever forget the bathtubs filled with blood or being grabbed (as I was) by an actor and pulled into a darkened room? That sense informs this production. The shock effects scare, but it is the underlying tension that makes the play so compelling.

Some have criticized Holloway’s script as dressing on which to hang the shock effects, but it is much better than that as it unravels the secrets of both Lou and James that may contribute to the nasty situation they find themselves in. Álvarez, who originated the role when the play premiered outside London in 2024, then played it in the West End, couldn’t be better. She has a vulnerability that draws you in that is so necessary for the play to work. And she has strong chemistry with Knight, who balances empathy with skepticism in dealing with his wife’s seeming psychological challenges.

When they become hermits in the second act, the play brings to mind Tracy Letts’s Bug in its depiction of a toxic, claustrophobic environment where paranoia completely overwhelms a couple. Though Lou’s and James’s adversary isn’t imaginary, the psychological infection is the same; the supernatural forces merely exploit the fractures already present in their isolation. What’s funny is that they don’t heed the advice of Etheline Cotgrave (Eva Kaminsky, excellent), whom they ask to assess the situation. During a séance, Cotgrave makes contact with the spirit, then gets more and more on edge only to leave abruptly with an exit line (that ends the first half) that should have had the couple heading to the nearest hotel. But, then again, if Cotgrave is to be believed, Lou and James have no exit. There is no escape from their nightmare, which ends with a final image that has haunted me for days.

Paranormal Activity continues through July 30 at the Emerson Colonial Theatre, 106 Boylston Street, Boston, MA. For ticket information, follow this link.