A Star Trek collection won't be complete without 'Star Trek IV: The Voyage Home.' This installment in the series concludes the story lines that began in 'Star Trek II: The Wrath of Khan,' and 'Star Trek III: The Search for Spock.' In this installment the Enterprise must take a trip back in time in order to save earth. Watch as they head back in time to find a humpback whale, since there are no humpback whales left on earth. Once they find the whale, they bring it back to the present and use it to help them save the Earth.