n the North Pacific, Sophia Assalas (Berenice Bejo) and her team have been tracking various shark species around the massive floating garbage patch full of fishing nets, debris, and discarded plastics, which have regularly ensnared baby sperm whales and disrupted marine life. Today, they’re attempting to relocate a tagged shark named Lilith, which has mysteriously more than doubled in size since they last encountered her. Unsettlingly, it’s not just a group of female mako sharks acting oddly that interferes with their mission; Lilith begins a rampage that kills four of Sophia’s divers. “Can’t let her get away again.”

Three years later, Sophia still suffers from the catastrophic loss of her crew. But when she’s approached by 20-year-old Mika (Lea Leviant) and hacker cohort Ben (Nagisa Morimoto), members of the ocean defense organization Save Our Seas (S.O.S.), she discovers another opportunity to revisit her former career. Beacon 7, which tracked Lilith, has turned up in the Seine, which means the oversized mako could be in Paris. Thanks to climate change and pollution, which have warped animal behaviors, it’s possible that the creature has wandered into the freshwater river, where it could begin a new terrorization of the populace.

“Isn’t it too late to save the oceans?” Although many nature-run-amok monster movies touch upon the neglect, disregard, and manmade disasters that cause Mother Earth to strike back (activist elements are indeed present here), “Under Paris” doesn’t care too much about the science. A killer shark is automatically a cinematic antagonist, which doesn’t require an attention to realism to hypnotize audiences. This is never more apparent than with the violence, gore, and the quantity of attacks, as well as the exceptionally bad CG embellishments of the unnaturally, lightning-fast fish. Visual thrills (feeble or otherwise) almost always surpass sensibility.

“Just stay calm.” Amusingly, the various moments of carnivore stalking are handled well, but only when they’re subtle, employing shadows and suggestions (and nearing movements with a pinging motion-tracking device, or dorsal fins cutting through surface tension). When the camera aggressively jerks to and fro, cheaply trying to manufacture suspense and panic, it’s far less convincing and effective (this goes for the physics-breaking shark lunges as well). Fortunately, much of the underwater photography is crystal clear and high quality; for the most part, the film sparkles.

“Make this little fish disappear!” But as political red tape and overconfident bureaucrats get in the way of shutting down civilian access (alongside the start of a timely triathlon and the Olympics), not unlike in “Jaws,” and overzealous organizers disobey authority figures, such as River Brigade police sergeant Adil (Nassim Lyes), the ensuing massacres grow increasingly silly. Nevertheless, it’s refreshing that everyone tends to take the scenarios seriously, refusing to crack jokes or add comic relief where it isn’t necessary. Still, once the “Mission: Impossible” type of suicide assignment approaches for a climactic showdown against the beast, the awkwardness of a CG monstrosity darting around escalates; the movements are terribly amateurish in their designs (especially when Lilith dodges bullets). At least viewers are given what they want, with the film culminating in the kind of bloody, extravagant chaos witnessed in the “Piranha” pictures of the 2010s, transforming into a full-on disaster movie of sorts.

– Mike Massie