The crew departs Vulcan aboard the Klingon Bird-of-Prey to Earth to face Federation Council charges. They arrive to find a space probe emanating strange sounds towards the planet, and apparently waiting for something. As time goes on, the probe starts to cause major storms on Earth and threaten its destruction. James Kirk and crew are called upon once again to save mankind. They discover the strange sound is actually the call of the humpback whale, which has been hunted to extinction. They have only one choice — to attempt to time travel back into the 20th century, locate a whale, and bring it back to 23rd century Earth to reply to the probe.

William Shatner (Admiral James T. Kirk)
Leonard Nimoy (Captain Spock)
DeForest Kelley (Dr. Leonard H. McCoy)
James Doohan (Capt. Montgomery Scott)
Walter Koenig (Cmdr. Pavel Chekov)
Nichelle Nichols (Cmdr. Uhura)
George Takei (Cmdr. Hikaru Sulu)
Jane Wyatt (Amanda Grayson)
Catherine Hicks (Dr. Gillian Taylor)
Mark Lenard (Ambassador Sarek)
Robin Curtis (Lt. Saavik)

Majel Barrett (Commander Christine Chapel)
Robert Ellenstein (The Federation Council President)
John Schuck (The Klingon Ambassador)
Brock Peters (Admiral Cartwright)
Grace Lee Whitney (Commander Janice Rand)
Michael Snyder (Starfleet Communications Officer)
Michael Berryman (Starfleet Display Officer)
Madge Sinclair (U.S.S. Saratoga Captain)
Mike Brislane (U.S.S. Saratoga Science Officer)
Nick Ramus (U.S.S. Saratoga Helm Officer)
Jane Wiedlin (U.S.S. Shepard Comm Officer Trillya)
Vijay Amritraj (U.S.S. Yorktown Captain Randolph)
Kirk Thatcher (Punk on Bus)

• This movie picks up where Star Trek III: The Search for Spock left off.
  
• Most of the shots of the whales used animatronic models.
  
• The unnamed captain of the U.S.S. Saratoga is the first female captain to be shown on screen. Madge Sinclair was uncredited for her cameo appearance.
  
• Although Kirk disobeyed direct orders and violated numerous Federation laws, the Council praises the Admiral and his crew for saving Earth. Kirk is demoted to Captain and given command of the newly-commissioned U.S.S. Enterprise NCC-1701-A.