A space probe appears over 23rd century Earth, emanating strange sounds towards the planet, and apparently waiting for something. As time goes on, the probe starts to cause major storms on Earth and threaten its destruction. James T. Kirk and crew are called upon once again to save mankind. They discover the strange sound is actually the call of the humpback whale - which has been hunted to extinction. They have only one choice - to attempt to time travel back into the 20th century, locate a whale, and bring it back to 23rd century Earth to reply to the probe.