The story of Gears of War 4 takes place 25 years after the events of Gears of War 3, where Adam Fenix, father of Marcus Fenix, flicked the weapon countermeasure to destroy the Imulsion killing Shining and Locust. This led to the elimination of all types of fossil fuels, forced humanity to adapt new ways to survive and brought the advent of powerful wind storms and fire that devastated the planet Sera. This is why the Coalition of Governments, to avoid extinction, he built walled cities to protect citizens from external dangers. The COG also declared martial law, preventing any travel outside of the walls of the city. Outside of these settlements were born in the fields of “Outsider”, outcasts trying to survive in hostile territories and live outside the COG jurisdiction by conducting raids on their territories to gather resources. The game focuses on Fenix Dominic James, son of Marcus Fenix and Anya Stroud, who alongside his friends Delmont “Del” Walker and Kait Diaz, faces a new threat to the survival of humanity.
The Coalition Government leaders, Prime Minister Jinn, commemorates the 25th anniversary of the victory of humanity against the Locust Horde. Meanwhile Hoffman, who is present at the ceremony, said the battles passed to Aspho Fields during the Pendulum Wars, the Emergence Day and Anvil Gate during the Locust War.
Meanwhile, JD and Del recently left the COG after disagreement with the hard Jinn policy to join a group of Outsiders led by Reyna. In order to help their village, the two boys decide to assault a COG settlement near under construction, to steal the maker and give energy to the electrical system of the village of Reyna. They are accompanied by Kait, daughter of Reyna, and her Uncle Oscar, a former Gear veteran of the Locust War. Even if you are forced to fight DeeBee, new robotic soldiers of the COG, JD and his group manage to steal successfully maker and flee to their village. Arrived, they are addressed by Jinn (transmitted via a DeeBee) accusing them of kidnapping his people, and then the village is attacked by an army of robot soldiers. JD and his friends manage to drive back the forces of Jinn and then, overnight, they repair the village power generator. However, in the midst of repairs, the strange creatures they raid the village, capturing all the inhabitants including Reyna and Oscar. Before disappearing, Reyna blocks JD, Del, and Kait inside the power plant to protect them.
After successful, JD decides to go with his friends in his old house to ask for help from his father, Marcus Fenix. Marcus, who is still angry with JD for joining the COG and for endangering himself, is riluttato to help his son, until he shows evidence of a new threat, the Swarm. Suspicious, Marcus decides to lead the group in Fort Reval, where thousands of Locust corpses were buried after the war. After another attack by the forces of Jinn and escape from the abode aboard two motorcycles Mule, the group reaches the fort, where they are attacked by the swarm and Marcus is kidnapped by a Snatcher. JD and his friends follow the Snatcher and discover that they are the perpetrators of the kidnapping of COG citizens mentioned by Jinn. Humans are captured and then collected to create the Army of the Swarm. They also speculate that the Locust are not dead when they are from the weapon countermeasure dell’Imulsion been affected, and that instead their bodies were subjected to a long-term transformation over the past 25 years, until the Locust is They have evolved into the Swarm. JD finally manages to track down Marcus and to free him. His father reveals that the Swarm operates on a hive mind, and that was briefly attached to it, and Reyna is still alive and held in another place of burial of the Locusts, but none of the other villagers survived.
Determined to save his mother, Kait demands that Marcus will take them from her. He leads the group to Tollern Dam, where they discover that the burial site has been transformed into a hive. Realizing that the hive defenses are too formidable for them, the group fights the Swarm to get to a radio antenna, where Marcus asks the assistance of Augustus Cole, Damon Baird and Samantha Byrne. It turns out that the last two are in love and that Baird was CEO of DB Industries, maker of DeeBee robot soldiers. JD and Kait climb aboard Jack Junior and Betty Two, mech robots manufactured by Baird, the road to get into the hive with the support by a King Raven, carrying the rest of the team. After facing a creature of the Swarm of enormous proportions, nested inside the