Hiatt Grey's Engines' celebrate Independence Day is an upcoming spin-off film to be made by Hiatt Grey.
On July 2, an enormous alien mothership that has one fourth the mass of the Moon enters orbit around Earth, deploying 36 smaller spacecraft, each 15 miles (24 km) wide, each taking position over one of Earth's major cities. David Levinson, an MIT-trained satellite technician, decodes a signal embedded in global satellite transmissions that he determines is a timer counting down to a coordinated attack. With the help of his former wife, White House Communications Director Constance Spano, Levinson and his father Julius, gain access to the Oval Office and warn President Thomas J. Whitmore that the aliens are hostile. Whitmore orders the evacuation of New York City, Los Angeles, and Washington D.C., but it is too late; the timer reaches zero and the ships activate devastating directed-energy weapons. Whitmore, the Levinsons, and a few others narrowly escape aboard Air Force One as the three cities, along with the other locations over which the ships are positioned are destroyed, killing millions.
On July 3, international leaders begin ordering counterattacks. Their aviation forces attack the destroyer ships above the ruins of the cities, but they are protected by force fields. Each destroyer launches a swarm of attack fighters with similar shields, which wipe out the human fighter squadrons. Captain Steven Hiller, a pilot with the USMC squadron VMFA-314based out of Marine Corps Air Station El Toro, survives the failed Los Angeles assault by luring his attacker to the enclosed spaces of the Grand Canyon and sacrificing his plane, forcing the alien to crash-land. He subdues the injured alien pilot and flags down a convoy of refugees, hitching a ride with former combat pilot Russell Casse. They transport the unconscious alien to nearby Area 51 where Whitmore's group has landed. Through Secretary of Defense Albert Nimzicki, they learned that a faction of the government has been involved in a UFO conspiracy since 1947, when one of the invaders' attack fighters crashed in Roswell. Area 51 houses the refurbished alien fighter and three alien corpses recovered from the crash.
When eccentric scientist Brackish Okun examines the alien captured by Hiller, it regains consciousness and attacks. It telepathically invades Okun's mind and uses his vocal cords to communicate with Whitmore before launching a psychic attack against him, but Secret Service agents and military personnel kill the alien. Whitmore explains he saw visions of the aliens' plans: their entire civilization travels from planet to planet, exterminating all indigenous life before harvesting the planet of natural resources. Whitmore reluctantly authorizes a nuclear attack; a B-2 Spirit fires a nuclear cruise missile at a destroyer positioned above Houston, but the ship remains intact.
On July 4, Levinson determines the key to defeating the aliens lies in deactivating their force fields, and devises a way to do so by uploading a computer virus into the mothership using the refurbished alien fighter, which Hiller volunteers to pilot. Human resistance forces around the world are informed of the plan. With military pilots in short supply, Whitmore enlists the help of volunteers with flight experience, including Casse, and leads an attack on a destroyer ship bearing down on Area 51. After the virus is uploaded, the aliens' shields are deactivated, and the fighters are able to inflict damage but their supply of missiles is quickly exhausted. As the destroyer prepares to fire on the base, the last missile, equipped on Casse's plane, jams, and Casse decides to sacrifice his own life. He flies his plane kamikaze-style into the directed-energy weapon, resulting in an explosion that destroys the ship. The other resistance forces are informed of this vulnerability, allowing them to destroy the other ships. Meanwhile, Levinson and Hiller deploy a nuclear weapon on board the mothership, escaping before it is destroyed. As humankind rejoices in victory, they return to Area 51 unharmed and reunite with their families. They and military officers nearby accompany Whitmore and his daughter in watching the wreckage from the mothership burn up, resembling a fireworks display as it enters Earth's atmosphere.
- Dile, Morley, Blitzer, July, and Sapphire guest star in this film.
- The storyline continues in Hiatt Grey's Engines' Adventures of Independence Day: Resurgence.