Star Trek IV: The Voyage Home

While returning to stand court-martial for their actions in rescuing Spock, Kirk and crew learn that Earth is under siege by a giant probe that is transmitting a destructive signal, attempting to communicate with the now-extinct species of humpback whales. To save the planet, the crew must time-travel back to the late 20th century to obtain a mating pair of these whales, and a marine biologist (Catherine Hicks) to care for them.