Synopsis

In the 23rd century, a mysterious probe suddenly appears on a direct course for Earth and begins disabling everything in it's path. Meanwhile on the planet Vulcan, Admiral James T. Kirk and the crew decide to go home and face punishment for their unauthorized mission to the Genesis planet to rescue Captain Spock. As they begin their return to Earth in the Klingon Bird of Prey, the probe already arrives there and it's signal causes the planet's power systems to lose power and block out the sun. The probe's signal is directed at the oceans. The Federation sends a warning about the probe and after Admiral Kirk receives it, Spock uses the ship's computer to determine if his theory, that the probe is signaling a creature in Earth's ocean, is correct. Spock's research proves that it is directed at humpback whales, which have been extinct for centuries. To save Earth, the crew must travel back in time to find humpback whales to reply to the signal. After a sling shot around the sun, the crew find themselves in 1986. Now they must find a pair of humpback whales and keep from being detected with only have 24 hours to save humanity.