"The Shallows" is a gripping story effectively told, whittled down to the core essentials of its suspense-laden mise en scéne. At its most basic, the film introduces a sympathetic protagonist, leads her to an exotic locale, and then quite literally strands her in a life-or-death situation from which there are no certain escape routes. Director Jaume Collet-Serra (2009's "Orphan") and screenwriter Anthony Jaswinski (2011's "Vanishing on 7th Street") tighten the screws of their minimalist premise to a riveting 87 minutes while placing the viewer squarely next to the lead character for the duration. "Jaws" meets "Cast Away" has been one description bandied about leading up to its release, and this is a decidedly accurate point of reference.

Nancy (Blake Lively) is at a crossroads. Still mourning the loss of her mother following an arduous cancer battle, she is no longer sure she wants to be a doctor and is grappling with the possibility of dropping out of med school. While trying to figure it out, she has come to Mexico in hopes of locating the secluded beach where her mom traveled during her pregnancy. An afternoon of catching some waves takes a sudden dire turn when she unknowingly enters a feeding ground and is attacked by a great white shark. Narrowly seeking safety on a rock located 200 yards from shore, Nancy has less than 24 hours to seek help or reach safety before the high tide submerges her perch.

"The Shallows" exudes no pretenses of being more than what it is: a primal tale of survival. Only the wraparound scenes ring false—the in medias res opening because it prematurely reveals a key development that occurs an hour later in the running time, and the epilogue because it is too tidy, expository and on the nose. The picture would have been even tauter without these flourishes, the final scene a virtual underlining of what didn't need to be spelled out at all. Everything else works like gangbusters, director Collet-Serra pulling one immediately into Nancy's present world—her existential inner conflicts, her outer ones with her dad (Brett Cullen) and younger sister (Sedona Legge) whom she Facetimes from the beach, and her desire to pay tribute to her late mother by making the very trek she is on. Her surgical skills and medical knowledge come in handy once she is thrust into a living nightmare scenario, but these things can only get her so far as a powerful, bloodthirsty shark circles her in the water.

An idyllic clear-watered paradise becomes a doomed man-vs.-nature prison as "The Shallows" strikes with sharp-toothed urgency and tension. The hook of the narrative is a doozy, portraying something that could happen to anyone who has ever placed their undue trust in the creatures swimming below the surface of the ocean. Acting alone for the bulk of the film is Blake Lively (2015's "The Age of Adaline"), an actor who has indelibly come into her own in recent years. She carries every second of the movie as Nancy, finding resourcefulness and strength while remaining pragmatic of her troubling circumstances. Lively is innately compelling and, here, exceedingly identifiable. Her willingness to help an injured seagull sharing the rock with her might seem like a small point, but it gives additional depth and empathy to a character on whose side we want to be. As for the heavy of the piece, a vicious shark who is really only doing what he is meant to do, it is brought to unnerving life through almost always seamless computer-generated effects artistry. At no point does it feel as if Lively is interacting with thin air, the shark posing a constant, crucial, methodic threat. Thriving on its straightforward simplicity and sheer pins-and-needles force, "The Shallows" is a crackerjack summer thriller.