Heading an international secret organization named Project Mayflower -not explained in the movie, but the novelization-, Claude Lacombe is a French scientist who is looking for all evidence of UFO's activity across the world, trying contact with it. His mission moves Mayflower to Sonoran Desert, New Mexico, where Flight 19, a military squad planes missing since 1945 have appeared safe and sound with any signal of aging or wear but without a trace of the pilots, meanwhile that UFO's activity increases in places as in Indianapolis Flight Center, seeing as some planes they detect report about it. Unaware for him, Roy Neary is a family man married with Ronnie and father of three children (Toby, Brad and Silvia) working as an electric lineman in Muncie, Indiana, who is forced to work at night when a sudden blackout happens in the city. Riding in his pick-up and checking the different electric lines along the road close to Muncie, in a train crossroad Roy lives a shocking experience when he watches in the night skies an UFO over him that it disrupts the pick-up, making that Neary follows it as fast as be possible after the pick-up turns normal. Close to there, artistic painter and single mother Jillian Guiler wakes up in the middle of the night to learn that her little and only son Barry isn't in his bed and he came out from the house, missing in the dark. Running behind him, Jillian arrives at a point of the road where Barry is almost run over by Roy. Saving her child in the last moment, Jillian takes Barry off the road and Roy comes out the pick-up to test if both are safe. Second later, some little UFOs fly over all them, and Roy follows them at the same time that some police cars, but finally UFOs leave the road to fly high and miss in the clouds. Back to home, Roy tells Ronnie the happened, meanwhile Lacombe travels to the Gobi Desert where Mayflower finds the ship Cotopaxi missing close to Cuba in 1925, and subsequently to India, where they record a large group of people singing the same chorus, apparently came from the sky. At the same time that Lacombe and his team investigate India's sounds looking to know its meaning, Roy's life is falling down. He backs to the place where she met Jillian, finding her and a group of UFO's believers who try to contact it, and he turns an obsessive to cut any UFO's news in the newspaper, causing that Ronnie rejects the change happened in her husband, worsened when she takes a phone call to communicate that Roy has been fired from his job. Things worsen too for Jillian, when UFOs visit her home and Barry is abducted by them despite to Jillian's efforts to save him. Abandoned by Ronnie and his children, obsessed with a strange shape he sees at any place since his encounter in the crossroad, Roy finally realizes by chance that the shape is Devil's Tower, Wyoming, where he drives to find questions. Not believing the news about a train wreck with toxic gas close to Devil's Tower -in true, a hoax created by Mayflower to keep people outside the mount-, Roy meets again Jillian in Moorcroft, WY, who too saw the same shape, and they both try discover the truth behind their experiences for arrive to Devil's Tower, not knowing that it will be the most important travel of their lives.