On July 2, 1996, an enormous alien mothership arrives in the orbit of the Earth and deploys multiple saucers, each fifteen miles wide, that take positions over Earth's major cities. David Levinson, an MIT-trained satellite technician, decodes a signal embedded within global satellite transmissions, realizing it is the aliens' countdown timer for a coordinated attack. With help from his ex-wife, White House Communications Director Constance Spano, David and his father Julius gain access to the Oval Office and alert President Thomas Whitmore to the threat. Whitmore orders evacuations of New York City, Los Angeles, and Washington, D.C., but it is too late. Each of the saucers fires a single destructive beam, causing a gargantuan explosion that incinerates each saucer's targeted city, killing millions. Whitmore, the Levinsons, and a few others escape aboard Air Force One as the capital is destroyed along with New York, Los Angeles, and other major cities around the world.