The underlining plot to Significant Other -- the latest horror/thriller movie streaming on Paramount+ -- is an engaging one, an interesting set-up to a potentially darkly hilarious sci-fi movie or a paranoia-infused horror film set in an endless stretch of woods. However, the film, written and directed by the team of Dan Berk and Robert Olsen, tries to juggle the two different tones even to the overall film's detriment. Luckily, the tonal mishmash is elevated by the film's stars and the solid writing, which both latch onto the story's inherent humanity to great effect and keep the focus on the characters.

The plot largely revolves around Ruth (Maika Monroe) and Harry (Jake Lacy), a couple going on a camping trip deep into the woods. Things get complicated, though, when Harry proposes to his long-term girlfriend, unsettling her and setting off her intense anxiety. The pair try to salvage the trip, but tension mounts between them. The next morning Ruth makes a horrifying discovery that changes the entire trajectory of the film, setting up an intense game of cat-and-mouse that slowly reveals more and more about Ruth and Harry's experiences with love, humanity, and pain.

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Maika Monroe as Ruth and Jake Lacy as Harry in Significant Other

Significant Other is primarily focused on just Ruth and Harry, leaving almost all of the film's dramatic and comedic heavy-lifting to Monroe and Lacy. Luckily, both have a great time filling out the pair. Monroe -- a veteran of horror films like It Follows -- explores the depths of Ruth's trauma and feelings with a well-natured but defiant edge that makes her surprisingly compelling, while Harry goes from extreme dramatic beats to overtly silly throughlines, even becoming threatening and unsettling when he needs to be. The pair find a good rapport in the film's rapidly evolving tones, shifting easily from one set-up to another. Their character beats are well-constructed, and they make for an entertaining pair.

The tonal balancing act of the film's second half is a bit tricker for Significant Other to handle, however. While it never becomes disjointed in direction, the film takes some wild swings from a dark comedy about an unexpected layer to their relationship to a more introspective exploration of love and pain. The shifts in tone introduce some interesting layers to the film and never become actively bad, but they leave the second half feeling oddly disjointed, spending a large swath of the second act as a tense tale that suddenly becomes an almost goofy riff on a fun horror trope.

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Maika Monroe as Ruth in Significant Other

If this had been the big film shift, and it had fully committed to that edge, Significant Other could have been a great comedy with a horrific edge. However, the third act changes back to the more introspective tone of the film's first half, shifting gears into a more unsettling and dramatic story. If the first act of Significant Other had cemented that balance more thoroughly, or if the film hadn't returned so bluntly to the more dramatic edges for its poignant ending, it might have all come together better. It's not like the shift ruins an otherwise good film, either, as the film is consistently well-directed and well-written.

The cast elevates the material and keeps everything grounded despite the tonal shift, and they manage to keep the characters consistent throughout. It's just that the story feels oddly disjointed when a tighter focus could have improved the narrative shift. There are two good movies stuck together in Significant Other, but just focusing on one of them would have likely been a better result.

Significant Other premieres Oct. 7 on Paramount+.