As Shelby Gilmore, the owner of a luxurious hotel on a stunning Pacific island, prepares to pop the question to his secretary, Kay Kirby, he remains oblivious to her true feelings for Hank Anderson, an oil rig worker who is being warned by his team about the imminent threat posed by their surroundings. Despite Shelby's intentions, Kay's heart is solely devoted to the rugged and dedicated Hank. At the same time, Hank's crew is urgently raising alarms about the volcano Mauna Lani, which is on the brink of a catastrophic eruption.
Bob Spangler, Shelby's trusted associate, comforts their hotel guests by assuring them that the volcano's threat is merely a wild rumor, downplaying the rarity of such eruptions, which only occur once every thousand years. However, what Spangler does not reveal is his own tangled web of lies: he is having an affair with Iolani, the hotel's executive, who is engaged to Brian, the general manager. This situation is further complicated by the fact that Brian is actually Spangler's secret younger half-brother and co-owner of the resort.
The hotel is home to a colorful cast of characters, including Francis Fendly, a seasoned bonds smuggler evading Tom Conti, a resourceful private investigator from New York City, and the retired tightrope walking duo Rene and Rose Valdez. On the work front, Hank's oil rig employees, like Tiny Baker, are preoccupied with their own personal ventures; Tiny is in a risky bet involving a prized rooster, a gamble that pales in comparison to the impending disaster.
Just as Hank and Kay set off for a romantic beach picnic to discuss their relationship, the volcano erupts, bringing devastation to the island and obliterating most of its inhabitants. A tsunami engulfs Tiny and his co-workers, while Sam escapes with his wife Mona and their two "bar girls," Delores and Marsha. In a daring move, Hank and Kay manage to evacuate Nikki and others from the stables, using a helicopter as chaos unfolds around them.
The only individuals who find refuge are those sheltered within Shelby's hotel, blissfully unaware of the destruction path ahead as Mauna Lani continues to rain fireballs. Conti suffers severe injuries from a fireball collision, blinding him and traumatizing Fendly with the sight of his suffering. Thankfully, paramedics assure him that his vision will eventually recover.
As the tension escalates among the remaining guests at the hotel, some make desperate attempts to escape via helicopter, resulting in a tragic crash that leaves no survivors. Amid the ensuing chaos, Hank's pleas for evacuation go unanswered, but a courageous group, including Shelby, Brian, Rene, Rose, Fendly, Conti, Sam, Mona, and her daughters, take the warning seriously and embark on a perilous journey to the island's safer shore. Unfortunately, Spangler’s persistence convinces most guests to stay, including his mistress Iolani, creating a stark division between the two factions as Shelby bids a bittersweet farewell to Nikki, who insists on staying with her husband despite the looming danger.
As this small group sets out, they face treacherous routes, including a daunting mountainside gorge that forces them to cross on foot. In an unexpected turn of events, Conti aligns with Fendly, establishing an uneasy partnership as they navigate the turmoil.
Their expedition leads them across a shaky wooden bridge hanging over a river of molten lava, with Hank taking the lead and carefully testing the bridge’s endurance. Each step grows more intense as every traveler races to safety. Amidst the upheaval, two native children, orphaned in this chaos, flee in sheer fright. Tragedy strikes when Sam and Marsha fall victim to an explosion, plummeting into the lava below.
In a moment of unexpected bravery, Rene utilizes his tightrope skills to rescue one of the lost children, while Hank manages to calm and guide the second child through the danger. Eventually, the survivors find shelter in a nearby cavern, facing the awe-inspiring yet frightening spectacle of fireballs lighting up the darkened sky. Spangler's arrogance seals his fate as one colossal fireball crashes down on the hotel, incinerating all that remains within.
The following morning, the sobering reality sets in as the remaining survivors make their way to the beach, greeted by two ships from Fiji ready to whisk them away to safety.
