Star Trek IV: The Voyage Home (1986) | Leonard Nimoy

Star Trek IV starts with our heroes on planet Vulcan, loading up to go home and face punishment from the Federation for their hijacking of the Enterprise and its subsequent destruction, as well as the sabotage of the Excelsior.  As they approach Earth, they find that a giant space probe is threatening to destroy the planet, emitting a signal that those on Earth are baffled how to respond to.  It is determined that the probe is sending messages in the language of humpback whales, which have been extinct for over 200 years.  With seemingly no obvious solution, Kirk and crew decide to time warp back to the late 20th Century to snatch a couple of humpbacks to bring back with them in the hopes of saving the Earth.  They discover two whales in captivity at a San Francisco Cetacean institute. Still, they have only a limited amount of time to figure out how to transport these whales in tons of seawater, in addition to needing to harvest enough nuclear energy to send their tapped out ship back to the future. Leonard Nimoy directs.