The episode begins in March 3, 1946. A young girl, Maia Rutledge (Conchita Campbell) of Crescent City, California, is with her parents in their car. Although it is raining outside, she persuades her parents to let her play nearby. While she is collecting flowers in the bushes, a light shines down on Maia, and she disappears. The next scene takes place on May 11, 1951 in South Korea. A young black soldier, Richard Tyler (Mahershalalhashbaz Ali), is being beaten by his fellow officers. One of them remarks, 'We treated you like an equal, but that wasn't good enough for you. You had to cross the line. A fellow soldier then drops a photo booth strip on the floor; the pictures are of Richard with a young white woman. Moments later, the same light which abducted Maia shines on Richard, and he vanishes.
Next, two teenagers, Shawn (Patrick Flueger) and Kyle (Chad Faust), are on a beach in the year 2001, drinking beers at night and talking about their personal lives. The light shines on them, and Kyle drops to the ground unconscious. The episode jumps to the present day with Kyle in a hospital bed, hooked up to a respirator. His father, Tom (Joel Gretsch), is comforting him.
Elsewhere, Diana Skouris receives a call on her cell from Dennis Ryland (Peter Coyote) telling her to Get over here, now! As Diana arrives at NTAC, Ryland announces that the country is at DEFCON One. Diana asks to be brought up to speed, and an unnamed co-worker tells her that the comet is no longer a fly-by; it is heading toward the earth. Countries around the world begin deploying missiles in an attempt to destroy the comet.
As it enters the atmosphere of Earth, Diana (Jacqueline McKenzie) remarks that the comet is slowing down, 'as if it's coming in for a landing.' As she tells Ryland the co-ordinates of where the comet's trajectory will land it, Dennis states that it is near Mount Rainier, their 'back yard.' Arriving at the landing spot of the comet, a multitude of cameramen and reporters have set up. Diana looks on as the comet slowly comes in to land, hovering over a lake and causing ripples to form in the water. While emitting a sound, the comet begins to shrivel and lose its cohesion. Seconds later, the ball of light explodes, sending a shock-wave that knocks over the onlookers. Returning to their feet, they discover the comet is gone, and thousands of people have appeared.
Back at NTAC, Tom and Dennis argue in Dennis' office. Tom tells him he needs answers, and that he will come through for Dennis. After this Dennis introduces Tom to Diana, explaining how, together, they will make a good team investigating the return of the 4400.