When a massive tectonic shift triggers a tsunami capable of swallowing whole continents, the military creates an ark capable of holding only 50,000 people and the DNA of every species possible while the storm consumes most of the world.
Renegade Soviet military officers steal a nuclear missile, launching it at the Soviet city of Donetsk from Turkey. Soviet defense systems, believing a NATO attack is in progress, order an immediate launch of ICBMs and SLBMs at the United States.
The SS Poseidon, an ocean liner slated for retirement and scrapping, makes her way across the Atlantic Ocean and the Mediterranean Sea from New York City to Athens. Despite protests from Captain Harrison, who fears for the ship's safety, the representative of her new owners, Mr. Linarcos, insists that she make full speed towards her destination to save money, preventing her from taking on additional ballast.
The plot centers on the SS Poseidon, a 135,000-ton state-of-the-art luxury cruise ship on a cruise from Cape Town, South Africa to Sydney, Australia as well as the stories and dramas of some of the 3,700 passengers and crew.
The O'Leary family are travelling to Chicago to start a new life when Patrick O'Leary tries to race a steam train in his wagon. He is killed when his horses bolt. His wife Molly and their three boys are left to survive on their own. In town she agrees to prove her skills as a laundress when a woman's dress is accidentally spattered with mud. She quickly proves herself and builds up a laundry business in an area known as "the Patch". Her sons are educated. One, Jack, becomes a reforming lawyer, but another, Dion, is involved in gambling. While washing a sheet, Mrs O'Leary discovers a drawing, apparently created by Gil Warren, a devious local businessman. Her sons realise that it reveals that he has a plan to run a tramline along a street that he and his cronies intend to buy up cheaply.
A group of soldiers led by Maj. Baker (Bradford Dillman) is ordered to investigate a basement level station which they believed was attacked. After Baker contacts his commander, Gen. Slater (Richard Widmark), they begin to investigate who drove a civilian van into the base. It is revealed to be owned by a scientist named Dr. Bradford Crane (Michael Caine), the only survivor of the attack. Slater orders two helicopters to check for a black mass (revealed to be bees), but the two helicopters are swarmed by the bees and crash, killing the pilots inside. Crane insists to Slater that the base was attacked by the same African killer bees that destroyed the helicopters. Helena Anderson (Katharine Ross), one of the base's doctors, supports Crane's story.
Kathie Rauch (Ruth Schudson), a psychic from Milwaukee, Wisconsin, sends a letter to the German Embassy in Washington, D.C. claiming the Hindenburg zeppelin will explode after flying over New York. In the meantime, Luftwaffe Colonel Franz Ritter (George C. Scott) boards with the intention of protecting the Hindenburg as various threats have been made to down the airship, which some see as a symbol of Nazi Germany.
As a passenger ship sails by the bleak ruins of a deserted island, Dr. Kersaint (Thomas Mitchell) blows his former home a kiss. When a fellow passenger asks him about the place, he tells its tragic story, segueing into a flashback.
Set in the 1920s in Pago Pago, Eastern Samoa, Charlotte, an American painter, arrives from Boston on the island of Alaya to visit her father, U. S. Navy Captain Bruckner, whom she hasn't seen in quite some time. Bruckner is the U.S. Congress-sanctioned Governor of the island, and he rules it with a stern, patrician, and thoroughly patronizing attitude towards the natives. Charlotte is somewhat taken aback by her father's rigid adherence to the law, particularly when she tries to intervene on behalf of Bruckner's charge/houseboy Matangi, who has involved Charlotte in a scheme to get Bruckner to toss out a harsh penalty issued to a native man who stole a boat "for love." Bruckner refuses, pish-poshing all this talk of love over the law, and severely reprimands Matangi, much to Charlotte's dismay.
David Koch (Jeff Fahey), a climatologist employed by Inter Sci, proposes a theory that the last ice age was triggered by Earth's polar shift in a single day. When unusually cold weather strikes Miami and the birds start to return from the south a few months earlier, he is sent to Antarctica to find out what is happening.
Four waves of increasingly deadly attacks have left most of Earth decimated. Against a backdrop of fear and distrust, Cassie is on the run, desperately trying to save her younger brother. As she prepares for the fifth wave, Cassie teams up with a young man who may become her final hope – if she can only trust him.
Figée dans les glaces de l'Antarctique depuis la préhistoire, une mante religieuse géante est libérée à la suite de la brisure d'un iceberg. Le monstre attaque alors New York, puis Washington. L'armée va devoir stopper l'insecte.
Yankee lawyer John Reynolds (Wayne) and Southern Belle Julie Mirbeau (Ona Munson) meet and fall in love on a riverboat going to New Orleans in the Gay Nineties. Upon arrival they are met by Julie's father (Henry Stephenson) who runs the popular Louisiana State Lottery Company and Reynold's Aunt Blanche (Helen Westley) who is a key figure in the anti-Lottery forces hoping Wayne as State's Attorney will end the Lottery.
In early 1950s southern California, Dr. Clayton Forrester (Gene Barry), a scientist who had worked on the Manhattan Project, is fishing with colleagues when a large object crashes near the town of Linda Rosa. At the impact site, he meets Sylvia Van Buren (Ann Robinson) and her uncle, Pastor Matthew Collins (Lewis Martin). Van Buren was told that the meteorite came down at a low angle, while Forrester observes it appears far lighter than normal for its massive size. His Geiger counter also detects it is slightly radioactive, but the object is still too hot to examine closely. Unable to account for these anomalies, Forrester is intrigued and decides to wait in town overnight for the object to cool down.
The narrator (Morgan Freeman) explains how humans were unaware that intelligent extraterrestrials were making plans to occupy Earth. Ray Ferrier (Tom Cruise) is a divorced crane operator longshoreman who works at a dock in Bayonne, NJ. Ray is estranged from his children. His former wife, Mary Ann (Miranda Otto), later drops off the children, 10-year-old daughter Rachel (Dakota Fanning) and teenage son Robbie (Justin Chatwin), at Ray's house in Bayonne on her way to visit her parents in Boston. Unexplained changes in the weather occur, emitting lightning that strikes multiple times in the middle of an intersection and disrupting all electrical technology in the area.