Everglow begins with the cute struggle of Kyung-hoon (Ji Hyun-woo), who visited Jeju to make a documentary about Jin-ok (Ko Doo-sim), a female diver. Kyunghoon’s work becomes a sincere mission for the souls buried in the deep sea and mountains.

Jeong-in, who recently divorced a violent husband, moves back to her hometown. While suffering from nosy villagers, she is soon drawn to Hye-jung, a newcomer to the town. Two young women soon get closer and Hye-jung’s freewheeling and confident character inspires Jeong-in to break free of her wretched life. One day, Hye-jung suggests Jeong-in share a ‘hobby’ with her, and now their bloody hobby is about to begin.

Set against the backdrop of the Jeju Uprising in 1948, which was sparked by an armed revolt of islanders fearing the division of Korea into North and South, the film portrays the tragic consequences of an indiscriminate punitive expedition by the South Korean government. Under the guise of an anti-communist campaign, more than 25,000 civilians were slaughtered. Through the story of a mother fiercely protecting her young daughter, the film highlights the resilience and strength of Jeju women amidst the chaos.

A South Korean Navy helicopter vanishes during a ROK-U.S. joint military exercise and crash-lands on a deserted island where time and space have collapsed. There, the crew encounters soldiers lost ten years earlier and comes face-to-face with the entity known as "It." To return home, they must survive and uncover the truth.