In Moose Ridge, Oregon, Keenan Tracey as Andrew Garsette, his two friends, Casey Dubois as Nick Miller and Andrea Brooks as Eliza, and his uncle Ryan Merriman as Pete Garsette, a local firefighter, prepare to meet Andrew's father and Pete's brother, U.S. President Sam Garsette, Tom Everett Scott who is coming home for the Fourth of July celebrations. Sam approaches on Marine One, but the helicopter is unexpectedly rerouted to nearby Dixon Airbase. Meanwhile, Emily Holmes as Celia Lehman, a SETI scientist, is informed of a mysterious signal heading toward Earth.
Suddenly, alien machines begin drilling through the surface from underground, and more alien drones shoot from the sky, appearing in places around the world. Pete convinces Secret Service agents to take the children away while he tries to help the townspeople. He finds Celia broken down on the side of the road and reluctantly agrees to bring her into town, but the town is already devastated; they decide to head to Dixon. Sam orders Vice President Dennis Brubaker and General Moore not to engage the ships without solid intel, but Marine One is shot down, and Brubaker assumes the presidency as Washington, D.C. is destroyed. Brubaker, with the reluctant approval of base officer Spears, Jill Teed as Spears, authorizes a counterattack while Michael Kopsa as General Moore weighs the risks.
Brubaker and Moore reach Dixon Airbase, and the plan to respond begins to unfold. Back in town, the Secret Service convoy is hit; agents are killed and Nick is injured. Andrew, Eliza and Nick reunite with Pete and Celia; they witness a dogfight between alien drones and fighter jets. The jets are no match for the attackers, but Pete manages to down one drone with Celia's phonon-emitting device. They reach Dixon and try to summon help, but a massive ship appears and Nick disappears, presumably killed.
Pete and Celia realize the device can disable the aliens by breaking their connection with the mothership, and they acquire an alien battery to boost its power. In a subsequent clash, the device is activated and the drones collapse, giving humanity a critical edge. Surviving a crash, Sam encounters Todd, a computer whiz played by Iain Belcher, who helps him contact Dixon with the aid of his friend Leni, portrayed by Grace Sherman. They confirm Sam's survival to Brubaker, who reveals that the alien mothership lies near the Moon, a discovery that raises the stakes for any offensive action. Sam resists ordering another nuclear strike on the ship; the drones surrounding the mothership intercept the missiles, and Moore warns that the invading force is releasing a gas that could make Earth uninhabitable within days.
A bold plan forms: a drone carrying the device will ascend to the mothership and, with a satellite signal, disable the drones' connections. Sam contacts a team of Army Rangers to launch missiles, while Andrew, Eliza, Todd and Leni work to send the activating signal from the ground. The effort is interrupted by an alien ambush, but Pete intervenes, igniting his truck’s fuel with a Roman candle and repairing the communications lines, allowing the kids to resend the signal. As missiles approach the ship, many are blocked again, yet the final payload manages to reach the mothership and destroy it. The explosion resembles a giant, dazzling firework, ending a tense chapter of the invasion, though the film closes with the looming presence of a larger alien fleet approaching Earth.
