 The plot involves a San Francisco health inspector and his colleague who discover that humans are being replaced by alien duplicates; each is a perfect copy of the person replaced, only devoid of human emotion.Released in the United States over the Christmas weekend 1978, "Invasion of the Body Snatchers" grossed nearly $25 million at the box office.It initially received varied reviews from critics, though its critical reception has significantly improved in subsequent years, receiving a 93% on Rotten Tomatoes and also being hailed as one of the greatest remakes ever as well as one of the best science-fiction horror films of all time.