The initial scenes didn’t grab me; they felt like an over-the-top version of "Kids from Fame." However, once the story found its footing, it became a pretty good mix of horror and science fiction thrills. The plot centers around a presentation given by a tech CEO, Kim Jong-tae, who is promoting ideas about shared communication and learning—a genuinely unsettling concept. This prompts Suh Yeong Cheol, played by Koo Hyo-hwan, to get even with the man he believes stole his groundbreaking concepts and then unfairly dismissed him. He injects the CEO with a serum that produces startling results and turns out to be highly contagious, causing those affected to grow teeth. The conference is happening near a shopping mall, so as these newly infected creatures spread, it creates problems for a group of shoppers who find refuge in one of the stores. As the behavior of the people outside evolves from simplemindedness to something much more organized, they realize that assistance isn't coming and they’ll have to rescue themselves. Fortunately, their phones still function, and among them is a professor, Se Jeong (Jun Ji-hyun), who attended the seminar. After consulting with her colleagues remotely, they decide they need to separate “Suh” from his protectors and utilize him as some kind of antidote. That proves easier said than done, but that’s what they set out to do. This is a tightly plotted and well-paced action adventure, enhanced by decent visual effects and an ensemble cast who work together to create a sense of confinement; it's reminiscent of "Poseidon Adventure," only with humans displaying savage behavior instead of rising water. The film explores the notion that the infected aren’t just aimlessly wandering around, but that there’s something more complex controlling them, which contributes significantly to the overall threat. It presents an enemy capable of improving itself each time one of its members learns something new. The filmmakers don't hesitate to eliminate some characters we are meant to be rooting for—particularly a young woman who convinced me a building like hers would be perfect for housing people who deserve to be taken out of society. The ending does lose momentum, devolving into something resembling a video-game style shootout, but the acting is solid and the film prompts several questions about technology's pervasive influence on our lives and how unprepared we are when it develops its own agenda.

Source on TMDB