After an Air Force squadron disappears over the Bermuda Triangle, two more planes are dispatched to discover what happened only to disappear as well. Meanwhile, Jessica, Jeff and Billy visit an aircraft carrier in the vicinity of the Triangle after being granted an interview with the ship's commander. With the situation becoming more dangerous, the Justice Magazine crew is ordered to leave the area, but their jet-copter disappears like the jet. The trio discovers a hidden dimension containing a prehistoric-like island in the Triangle. Jessica and her team explore the island, and after Jessica becomes Spider-Woman to deal with some dinosaurs, they discover a tribe of Neanderthals. They are using advanced technology and are under the control of a man named Dr. Morrison, who discovered the island thirty years ago and is preparing to take over the Earth. Spider-Woman attempts to free Jeff and Billy from Morrison but she too ends up as a captive along with the missing pilots. The doctor orders his cavemen to go to the Bermuda Triangle in his advanced jets and destroy the fleet stationed there. Spider-Woman escapes from her prison and stops the jets. However, Morrison then uses his mind-link device to control the actions of the island dinosaurs and sets them loose on New York. With the city overrun by the ancient reptiles, Spider-Woman must find a way of breaking Dr. Morrison's mind control over them, and save the city.