The year is 2011, and the world has seen better days. In Russia, a civil war is brewing between the Loyalists to the Government and an Ultranationalist rebellion looking to bring their country back to the glory days of the Soviet Union. In the Middle East, a coup d’état is brewing as the leader of OpFor, Khaled Al-Asad, wants to overthrow the Saudi Arabian president, Yasir Al-Fulani. Meanwhile, the Special Air Service (SAS) gets a recruit named John “Soap” MacTavish, with Captain John Price and his right-hand man Gaz testing the former in weapon firing and C.Q.B. After Soap passes both tests, he joins Price’s team in infiltrating a cargo ship in the Bering Strait and investigates a package leaving Russia. The team searches through the ship and uncovers a nuclear device. However, they are forced to leave with only the manifest when a group of MiG-29s shoot down the ship.
Meanwhile, Al-Asad’s coup comes into effect as Yasir Al-Fulani is captured and publicly executed by the former.
While the US Army prepares to invade Saudi Arabia and kill Al-Asad, the SAS goes to the Caucasus Mountains to rescue their Russian informant, Nikolai. Nikolai was last seen in the mountains detained by the Ultranationalists, and Price is determined to save him. With the help of a Loyalist squadron led by Sergeant Kamarov, Price’s squad successfully extracts Nikolai and heads for the Safehouse. On route, their helicopter is shot down by a SAM, forcing the group to run on foot through the countryside until they receive help from an AC-130 Spectre gunship. Afterwards, Price’s squad makes it to the extraction point.
Meanwhile, the USMC begin their invasion of Saudi Arabia to bring down Al-Asad and bring peace back to the country. Among the troops include members of the 1st Force Recon, led by Lieutenant Vasquez. Vasquez led his squadron, which included Sergeant Paul Jackson and Staff Sergeant Griggs, into the cities to find Al-Asad. After a dead end at Khafji, the Marines get word from Command that Al-Asad is in Basra, Iraq, and everyone is ordered to go. Jackson’s team stormed through the city, looking for Al-Asad, but the mission was halted when Seal Team 6 discovered a nuclear threat. Despite their best efforts to escape, even briefly saving a helicopter pilot after her Cobra is shot down, the nuclear bomb goes off, killing 30,000 lives, including Jackson and Vasquez.
One day later, Nikolai discovers Al-Asad hiding in Azerbaijan under the protection of the Ultranationalists. Price’s team searches through all the buildings in the village before eventually finding Al-Asad. As Price interrogates Al-Asad for information about the bomb, the latter’s cell phone rings, and Gaz gives it to Price. As soon as Price listens, he kills Al-Asad without a second thought with a furious Death Glare on his face and tells everyone who was on the line: Imran Zakhaev.
Price explains that Zakhaev was an arms dealer who sold nuclear material to the highest bidders before becoming the leader of the Ultranationalists. Fifteen years ago, the British Government authorized an assassination of Zakhaev and Price, who was a Lieutenant back then, joined Captain MacMillan in the mission. The duo snuck through the ruins of Pripyat, Ukraine, despite still being heavily contaminated with radioactive fallout from the Chernobyl Nuclear Power Plant disaster in 1986, before setting up their hideout in the Polissya Hotel above where Zakhaev was about to do his deal. Price shot at Zakhaev, but the bullet only ripped off the latter’s left arm, and he escaped. Price and MacMillan escaped through the city as the Ultranationalists attacked them. While MacMillan suffered severe leg injuries during the escape due to a crashing Mil Mi-28 Havoc, he and Price managed to get extracted safely.
Eight hours after Al-Asad’s death, Price’s group is overrun by Ultranationalists, but they manage to get extracted to safety thanks to Griggs and the Marines that did not die in the nuclear explosion. Now working as a joint operation, the SAS and Marines plan to capture Zakhaev’s son Viktor, hoping the latter could tell them where his father was hiding. While the group manages to corner Viktor on top of a building, the latter shoots himself in the head in defiance to protect his father, choosing Better to Die than Be Killed, scornfully telling them that they will all die soon enough before he takes his own life.
Angry that the SAS and Marines were responsible for the death of Viktor, Imran threatens to launch Russian nuclear missiles at the United States if they do not leave Russia. However, the group travels to the Altay Mountains to stop Zakhaev. While the missiles are launched, the group storms into the ICBM facility and use the abort codes to destroy the warheads midflight. As the group escapes, they are chased by Zakhaev’s Ultranationalists, following them to a bridge where they are halted by a Mil Mi-24 Hind destroying it. The group fights back, but a tanker blows up and knocks everyone off their feet. Zakhaev’s men kill Gaz and Griggs, but before they reach Soap, the Loyalists appear and distract them as a Havoc blows up the Ultranationalists' Hind. At that moment, Price slides Soap his M1911 and the latter uses it to kill Zakhaev. With the leader of the Ultranationalists dead, Soap and Price are airlifted out of Russia to seek medical treatment for their wounds by Kamarov and his men as they arrive in their Mil Mi-8 Hip transport helicopters. As for the situation with the nukes, the Russian Ministry of Defense releases a cover-up story to ensure there is no global paranoia from it and it was still within the United Nations' guidelines.
