Quick recap
In 2286, the crew exiled on Vulcan heads back to Earth to face a court-martial. On the way, they learn a giant probe is knocking out the planet's power and whipping up storms. Spock realizes its signal is the song of humpback whales, extinct for centuries. The answer is to go back in time. They land in 1986 San Francisco and split up: Kirk and Spock find two humpbacks at a Sausalito aquarium and biologist Gillian Taylor, Scotty gets a tank, and Uhura and Chekov hunt for power on a nuclear aircraft carrier. With the whales and Gillian aboard, they return to 2286. The whales answer, and the probe leaves. At the trial, Kirk is demoted to captain and gets a new ship: the Enterprise-A.

