Most shark horror movies operate based on a pretty simple concept: put a group of characters into a body of water, add a shark, and let the terror begin. Within the subgenre, there are plenty of attempts to be as creative as possible with that concept, sometimes stretching it so far beyond the realm of believability that it becomes a parody of itself. Other films stick to the basics, doing their best to wring as many scares as possible from the fear of what’s lurking underneath the ocean’s surface. Writer-director Andrew Traucki’s THE REEF: STALKED opts for the latter strategy, hoping that its characters are engaging enough and its shark-y scares are frightening enough to carry the film’s simple premise. Though it’s not the best of the subgenre and pales in comparison to its predecessor, 2010’s The Reef (which was also written and directed by Traucki), THE REEF: STALKED still succeeds, providing an effective bit of aquatic horror that should satisfy fans looking for new scares during Shark Week.

The film opens with a group of friends diving in the ocean: Jodie (Ann Truong), Lisa (Kate Lister), and sisters Cath (Bridget Burt) and Nic (Teressa Liane). Once they finish their excursion and part ways, Cath’s boyfriend Greg (Tim Ross) murders her by drowning her in their bathtub. (Forgive the whiplash: this transition is slightly less abrupt in the film, though not by much. It’s clear from the brief interactions we see between Cath and Greg that he is abusive, but the film moves fairly quickly to set up Nic’s trauma.) Nic, summoned by a distressing text from Cath, finds her sister’s body and endures one of far too many flashes of what Cath’s final moments must have been like: we see quick cuts of Cath flailing underneath the water and then staring up lifelessly.

Nine months later, Jodie, Lisa, and Nic decide to reunite for a kayaking trip in honor of Cath’s memory. Nic’s other sister, Annie (Saskia Archer), joins them, though she is far less experienced in the water than the others. Their trip takes a terrifying turn when a huge shark targets them and — as the title suggests — stalks them as they attempt to make it safely to shore.

Movies that spend so much time on a small, core group of characters live and die by the cast’s chemistry. Fortunately, the women all have an easy camaraderie that gets the viewer invested quickly in their friendships and their survival, and there’s a touch of The Descent in their resourceful attempts to stay alive. Wisely, the tension between Nic and Annie is never overplayed. Nic left town right after Cath died, leaving Annie to pick up the pieces with their grieving mother as Nic traveled the world, and the guilt, grief, and resentment between them make for a heartbreaking dynamic, particularly when Nic must work to protect Annie from the shark. Cath’s death hangs over all the characters like a shadow, giving THE REEF: STALKED a sense of melancholy that works well with the lurking threat of the shark. However, it missteps in its depiction of Nic’s trauma.

Since Cath’s death is the inciting incident, there’s no need to flash back to it as often as the film does. Every single character, and every single viewer, is well aware of the tragedy of her murder and the effect it had on Nic. By flashing back to Cath’s violent death several times — particularly in such a disorienting way, one that may bother photosensitive viewers — it becomes a spectacle rather than a source of psychic pain. Though Cath’s underwater thrashing is clearly meant to parallel the women’s struggles against the shark (and, if we stretch the metaphor close to breaking, Greg himself — and the trauma he represents — is meant to parallel the predatory beast stalking and ultimately destroying its prey), the film should trust the viewer enough to understand the similarities without shoving Cath’s death in our faces over and over.

Now to what is perhaps the most vital part of any shark movie: the shark scenes. Though it gets repetitive near the end, THE REEF: STALKED mines a lot of tension from its characters scanning the ocean’s surface; their panicked vigilance will raise the viewer’s pulse as the characters realize the giant, hungry animal hunting them could be absolutely anywhere. Many of the scenes unfold in real-time, accompanied by Mark Smythe’s ominous score, and the agonizing search for a glimpse of the shark is just as tense as the moments when its fin breaks the surface and approaches the women’s kayaks. Equally terrifying is a heartstopping aerial view of Jodie paddling as the shark’s shadowy figure trails behind her, along with the moments when the women’s vulnerable limbs dangle underwater, only to make it to the surface seconds before the shark’s jaws clamp around them.

When you’re in the ocean, the only thing worse than seeing a shark fin is seeing it disappear, and THE REEF: STALKED makes highly effective use of this knowledge. While there are better shark movies out there, its engaging characters and startling scares make it an enjoyable piece of aquatic horror. If you’re looking for teeth and blood, this may not be the movie for you, but if you have an appetite to see women banding together to survive, THE REEF: STALKED is a nice stretch of ocean to visit.

The film will be released In Theaters, on Digital/VOD, and streaming on Shudder on July 29, 2022.