In war-torn colonial America, in the midst of a bloody battle between British, the French and Native American allies, the aristocratic daughter of a British Colonel and her party are captured by a group of Huron warriors. Fortunately, a group of three Mohican trappers comes to their rescue.

Though she can spin wild tales of passionate romance, novelist Joan Wilder has no life of her own. Then one day adventure comes her way in the form of a mysterious package. It turns out that the parcel is the ransom she'll need to free her abducted sister, so Joan flies to South America to hand it over. But she gets on the wrong bus and winds up hopelessly stranded in the jungle.

When drillers on an offshore oil rig dredge up several prehistoric eggs, one man is attacked by what appears to be an unidentified deep-sea creature protecting them. Soon, strange symptoms and behaviors become apparent among the crew and one of the creatures grows to adult-size.

Madie is a neurotic, wealthy woman who escapes from a New York state mental hospital where her unwholesome husband had her committed to avoid the trial of a expensive divorce. Madie hitches a ride back to California with a certain Charles Callahan, a debt-ridden truck driver. Madie and Charles eventually fall in love while evading an assortment of bad guys including a pair of thugs hired by Madie's husband to prevent her from returning to California, and a repo man sent to reclaim Charles' truck

The film takes place aboard an American submarine in the Pacific during World War II. The sub's commander is ordered to stop and pick up an underwater demolition team led by Lt. Hayes, whose mission is to locate and destroy a US submarine sunken in a lagoon off Bikini Atoll before the Japanese are able to raise it and capture the advanced radar system on board.