A civilian oil rig crew is recruited to conduct a search and rescue effort when a nuclear submarine mysteriously sinks. One diver soon finds himself on a spectacular odyssey 25,000 feet below the ocean’s surface where he confronts a mysterious force that has the power to change the world or destroy it.
When Ripley’s lifepod is found by a salvage crew over 50 years later, she finds that terra-formers are on the very planet they found the alien species. When the company sends a family of colonists out to investigate her story, all contact is lost with the planet and colonists. They enlist Ripley and the colonial marines to return and search for answers.