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 the Star Trek science fiction television series and completes the story arc begun in Star Trek II: The Wrath of Khan and continued in Star Trek III: The Search for Spock. Intent on returning home to Earth to face trial for their crimes, 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. Nimoy and producer Harve Bennett conceived a story with an environmental message and no clear-cut villain. Bennett divided the story with writer and director Nicholas Meyer, getting approval from Nimoy, lead actor William Shatner and Paramount. 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 postproduction 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 film's humor and unconventional story were well received by critics, fans of the series and the general audience.