Following the decommissioning of the patrol vessel Nagare, Daisuke Senzaki Hideaki Ito, a Japan Coast Guard (JCG) rescue diver, is reassigned to the 10th Region Mobile Rescue Unit based at Kagoshima Air Station. When a plane crashes in stormy seas, he battles the elements to keep two victims alive aboard a wreckage that has become their lifeboat. He can only save one adult male, while a young boy struggles to hold on alone. He manages to keep the boy alive, but the heroic sacrifice of the man drowns, and Senzaki is left with guilt and self-doubt, haunted by a vow not to let any more victims die.
Senzaki’s girlfriend Kanna Izawa Ai Kato takes time off and travels a long distance to see him. They check into a hotel, where Izawa locks herself out of her room, forcing her to spring a handmade wedding dress surprise on Senzaki, accompanied by a fashion designer. Izawa intends to fulfill plans of marriage, but Senzaki, still traumatized, is not ready for a life together, and his reluctance begins to strain their relationship. Izawa leaves heartbroken, even as Senzaki’s friend and ally Tetsuya Yoshioka Ryuta Sato tries to mediate.
En route to a routine training exercise, news arrives that a passenger ferry, the Clover, has run aground with only four hours left to evacuate. Daisuke Senzaki Hideaki Ito and Tetsuya Yoshioka Ryuta Sato are among the first divers on site, deployed by helicopter. Coast Guard crisis command lays out a daunting figure—620 passengers and 195 fuel-laden vehicles, all with a ticking clock. The rescue effort takes a dramatic turn when Senzaki discovers Izawa aboard Clover. Izawa had chosen the ferry over a drive home, a fateful decision that complicates their bond. Senzaki urges Izawa to abandon her belongings and head for the lifeboats, including the handmade wedding dress. As they part, Izawa seeks reassurance that they will meet again afterward.
While tending to an injured, pregnant staff member, Megumi Honma Nene Otsuka, Senzaki becomes separated from the rest of his team as Honma points out a faster route to the escape hatches. The shortcut leads them to the vehicle deck, where they encounter an irritable passenger Shinichi Ebihara Mitsuru Fukikoshi, who is tending to his precious Ferrari. A sudden lurch ignites the petroleum, triggering a massive explosion. The four scramble for cover on another deck, disoriented and trapped, while Ebihara suffers an injury to his left thigh. They radio for help and discover a duct marked “68-4T,” the clue to a possible route of escape.
The crisis command center at shore scrambles to map a feasible plan, and Shimokawa—back in shore command—faces a hard choice: press on with a risky rescue of the four missing divers or pull back all teams to avoid further casualties. Explosions and casualties mount, and the on-site divers move to implement a difficult decision: some divers are withdrawn as the operation becomes increasingly perilous.
Back on shore, Izawa waits anxiously for news. When rescue efforts are officially suspended due to ongoing danger, she watches the Clover burn and waits for any radio confirmation. The scene underscores the uncertainty facing the command and the unresolved fate of the divers and passengers, leaving her to grapple with hope and fear as the rescue operation continues to hinge on perilous decisions.
