Star Trek IV: The Voyage Home is a 1986 American science fiction film released by Paramount Pictures. It is the fourth feature film based on Star Trek, and is a sequel to Star Trek III: The Search for Spock (1984). It completes the story arc begun in Star Trek II: The Wrath of Khan (1982) and continued in The Search for Spock. Intent on returning home to Earth to face trial for their actions in the previous film, the former crew of the USS Enterprise finds the planet in grave danger from an alien probe attempting to contact now-extinct humpback whales. The crew travel to Earth's past to find whales who can answer the probe's call.
After directing The Search for Spock, cast member Leonard Nimoy was asked to direct the next feature, and given greater freedom regarding the film's content. Nimoy and producer Harve Bennett conceived a story with an environmental message and no clear-cut villain. Dissatisfied with the first screenplay produced by Steve Meerson and Peter Krikes, Paramount hired The Wrath of Khan writer and director Nicholas Meyer. Meyer and Bennett divided the story between them and wrote different parts of the script, requiring approval from Nimoy, lead actor William Shatner, and Paramount. Principal photography commenced on February 24, 1986. Unlike previous Star Trek films, The Voyage Home was shot extensively on location; many real settings and buildings were used as stand-ins for scenes set around and in the city of San Francisco. Special effects firm Industrial Light & Magic (ILM) assisted in post-production and the film's special effects. Few of the humpback whales in the film were real: ILM devised full-size animatronics and small motorized models to stand in for the real creatures.
The Voyage Home was released on November 26, 1986 in North America, and became the top-grossing film at the weekend box office. The film's humor and unconventional story were well received by critics, fans of the series and the general audience. It was financially successful, earning $133 million worldwide. The film earned several awards and four Academy Award nominations for its cinematography and audio. It was dedicated to the crew of the Space Shuttle Challenger, which broke up 73 seconds after takeoff on the morning of January 28, 1986. Principal photography for The Voyage Home began four weeks after Challenger and its crew were lost.