Systems analyst and efficiency expert Warren Lasky boards a military helicopter at Pearl Harbor, Hawaii, and is transported to the aircraft carrier U.S.S. Nimitz, in the middle of the ocean, to begin his assignment. Capt. Matthew Yelland remarks that the ship’s journey is delayed two days because of Warren’s mysterious boss, Mr. Tideman, and now a storm is brewing. Warren wanders into the office of Cdr. Richard Owens and notices that the Commander is writing a historical account on the attack at Pearl Harbor. On the bridge, radio communications are garbled and Ofc. Black Cloud reports bizarre weather patterns. As the crew watches the electrical storm, a vortex of light accompanied by a deafening roar and bolts of lightning engulf the ship. After the storm, the crew regains consciousness, but radio communications are down. Suddenly, the radio signalman receives an outdated code he learned in training school but is no longer used. Yelland orders his men to be on full alert because the strange goings-on could mean a threat of war. Although the ship’s communications systems appear to be normal, only old Jack Benny radio broadcasts can be heard on them. On a yacht, Sen. Samuel Chapman and his political operative, Arthur, polish a speech for Sam’s nomination as Vice President of the United States and running mate of Franklin D. Roosevelt. Suddenly, two U.S.S. Nimitz fighter jets fly overhead, and Sam tells Laurel Scott, his assistant, to make inquiries to the military about the suspicious planes once they reach shore. On deck of the U.S.S. Nimitz, Yelland theorizes that someone from Warren’s office is playing a joke, but Warren denies the accusation. Yellen is then called away to look at aerial reconnaissance photographs of Pearl Harbor. Cdr. Dan Thurman says the photos are fakes, but Yelland points out that an intact U.S.S. Arizona, is resting in the harbor before its destruction by the Japanese. Warren then is summoned to the bridge, where he advises Yelland to compare the new photographs with the historical images from Owens’ manuscript. When they compare the pre-WW II archival Smithsonian photographs with Yelland’s pictures, they see that the images are almost identical. Owens points out that Yelland’s shots show Pearl Harbor as it appeared on 6 Dec 1941, but it hasn’t looked that way in forty years. Soon, some of Yelland’s fighter planes radio that they’ve seen mint condition WW II Japanese Zero planes flying in the sky. Yelland orders his pilots to watch them. Although the captain thinks the vintage planes are somebody’s idea of a joke, Warren poses that the ship has traveled back in time. However, Yelland doesn’t believe him. On the yacht, Sam, Laurel and Arthur spot the Japanese fighter planes, which circle around and shoot at the craft, killing Arthur as the others jump into the ocean. The Zeros blow up the yacht and return to kill the other passengers, but Sam, Laurel, and her dog survive after submerging underwater while the captain dies. Afterward, Yelland’s pilots blow the Zeros out of sky. Meanwhile, as planes from Yelland’s fighter squad find the rest of the Japanese fleet waiting to attack, Yelland’s crew rescues the passengers and Laurel’s dog from the water. Recognizing the senator, Owens realizes that time has shifted into the past. As a Japanese pilot is taken prisoner, Yelland and his officers debate getting involved and changing the course of history. Foremost, Yelland argues that it is their job to defend the U.S. from attack. However, Warren reads through Owens’ manuscript and discovers that they have already changed history by rescuing the senator. Soon, Laurel’s dog causes a disturbance, and the Japanese pilot grabs a guard’s rifle and kills him. As the Japanese pilot takes Laurel hostage, crew member Lt. Kajima translates that the pilot wants a radio. When Yelland orders Owens to reveal the attack plan for Pearl Harbor, the Japanese pilot lowers his gun in disbelief, and is shot dead by crew members. Meanwhile, Sam wonders how Owens knows classified information and insists that they radio the base. However, the radio operator accuses Sam of being an imposter because the military has no air carrier U.S.S. Nimitz commanded by Yelland on record. Frustrated, Sam demands to be flown to Pearl Harbor. Yelland agrees, but Warren reminds him that he’s tampering with history. Yelland replies he wants civilians off the ship if war breaks out, and is less concerned with historical details. Yelland orders Owens to take Laurel and Sam to a less strategic island where they will be safe from attack, then broadcasts a message to his crew, explaining their strange predicament and alerting them to prepare for the attack on Pearl Harbor. Sam is angry when he sees that he and Laurel are not being escorted to Pearl Harbor, so he hijacks the helicopter with a flare gun, demanding that the pilot fly him alone to the base. As the helicopter takes off, Owens tries to climb on board to stop Sam, but he falls into the ocean. As a crew member wrestles the flare gun away from Sam, the gun fires and the helicopter explodes. Meanwhile, Yelland orders a squad of planes to head off the Japanese fleet. On the beach, Laurel and Owens see a formation of Zeros heading toward Pearl Harbor. The U.S.S. Nimitz crew watches a new vortex forming, similar to the storm that sent them back in time. The new storm forces Yelland to abort the mission to save his men. A deafening roar passes over the ship. Soon, the fighter planes return intact and the ship returns to the present day. Warren leaves the ship to where a limousine is waiting with his mysterious boss, Mr. Tideman, inside. When the window lowers, he sees Tideman is an older Owens, along with his wife, the former Laurel Scott. Warren gets in the limo with his employers, who want to explain the past forty years, as they all ride off together.