On June 23, 2018, twelve boys of the junior football team "Wild Boars" and their assistant coach Ekkaphon Chanthawong leave practice to explore the Tham Luang cave. When the team fail to arrive at a birthday party organised by their parents, their families head to the caves, only to find them flooded and the boys missing, their bikes left at the entrance. The parents immediately alert emergency services.

Royal Thai Navy SEALs, led by Captain Arnont, arrive to search for the missing boys, but find the dive too difficult to locate the team. Vernon Unsworth, a local British caver, shares his extensive knowledge of the complex and dangerous cave and suggests the authorities get in touch with the British Cave Rescue Council. British cavers Rick Stanton and John Volanthen attempt the dive, finding the boys and coach four kilometres from the entrance. In an attempt to deliver wetsuits to the boys in preparation for the rescue, former Thai Navy Seal Saman Kunan drowns.

Meanwhile, as hundreds of volunteers try to mitigate poor weather conditions, a water technician from Bangkok gains the permission of local farmers to divert water from the mountain onto their fields, destroying their crop.

Realising the boys will have to be removed through the cave, via a 6 hour dive, Stanton and Volanthen contact Dr. Richard Harris, plus supporting divers Chris Jewell and Jason Mallinson. With permission from the regional governor and minister, the divers sedate the boys and, with one diver per boy, carry each member out of the cave safely. The coach is removed last. Removed to hospital, the parents are reunited with the team. The end scene is the boys celebrating the birthday party that was supposed to happen on the day they went into the cave. The end credits reveal that the coach and three of the boys, who were all stateless, are given Thai citizenship. The film is dedicated to Saman Kunan, the Thai Navy Seal who died while resupplying air tanks on July 6, 2018. The credits also mention another Navy Seal, Beirut Pakbara, who later died from a blood infection.