The Whale Probe Crisis

In 2286 a vast cylindrical probe of unknown origin entered the Sol system broadcasting a signal toward Earth's oceans. Its transmissions drained power from every vessel in its path and began boiling the seas and darkening the skies, leaving the planet on the brink of catastrophe. Starfleet Command issued a planetary distress call warning all ships to stay away.

Returning from Vulcan aboard a captured Klingon Bird-of-Prey, Kirk and his former Enterprise officers realized the signal matched the song of humpback whales, a species hunted to extinction centuries earlier. Spock calculated a slingshot maneuver around the Sun that carried the ship back to San Francisco in 1986. There the crew found two whales, George and Gracie, with the help of cetacean biologist Gillian Taylor, and brought them forward to the 23rd century.

Once released into the ocean, the whales answered the probe, which ceased its assault and departed. The charges facing Kirk's crew for their earlier actions were largely dropped; Kirk was demoted to captain and given command of a new ship, the USS Enterprise NCC-1701-A.