Despite the efforts of the United States Marine Corps and the Special Air Service, the Ultranationalists seize control of Russia and declare Imran Zakhaev a hero and martyr, erecting a statue of him in the heart of Red Square. Meanwhile, Vladimir Makarov, one of Zakhaev’s former lieutenants, begins a campaign against the West by committing acts of terrorism over the course of five years.
Player character Sergeant Gary “Roach” Sanderson riding a snowmobile in the “Cliffhanger” level.In Afghanistan, U.S. Army Ranger Private First Class Joseph Allen assists in taking a city from insurgents. Impressed by Allen’s combat abilities, Lieutenant General Shepherd recruits him into Task Force 141, an elite, multi-national counter-terrorist unit under Shepherd’s command. Meanwhile, two other members of Task Force 141, Captain John “Soap” MacTavish and Sergeant Gary “Roach” Sanderson infiltrate a Russian airbase in the Tian Shan mountains to retrieve an Attack Characterization System (ACS) module from a downed satellite.
Allen is later sent on an undercover mission in Russia for the CIA under the name Alexei Borodin, joining Makarov in a massacre of civilians at the Zakhaev International Airport in Moscow. Makarov has been aware of Allen’s identity and kills him during extraction, leaving his body behind to spark a war between Russia and the United States. Angered by what was believed to be an American-supported terrorist attack, Russia retaliates with a massive surprise invasion on the United States after bypassing its early warning system, revealing that the ACS module had already been compromised before its retrieval. Sergeant Foley leads his squad of Army Rangers, including Pvt. James Ramirez, in defense of a suburb in northeastern Virginia against the invasion. They then proceed towards Washington, D.C., where more U.S. forces are fighting against the Russians for control of the capital.
Meanwhile, Task Force 141 searches for evidence that implicates Makarov as the mastermind behind the airport massacre, as proof of Makarov’s involvement died with Allen. Intelligence leads them to a favela in Rio de Janeiro, where the team investigates Makarov’s contact, weapons dealer Alejandro Rojas. They find out from Rojas that Makarov’s worst enemy, known as Prisoner 627, is incarcerated in a Russian gulag east of Petropavlovsk. Task Force 141 assaults the prison and manages to free 627, who turns out to be Captain Price. Price agrees to aid the 141 and Shepherd in tracking down Makarov, but argues that the war in America needs to end before the 141 can do so. To end it, he temporarily goes rogue, and leads the 141 to raid a Russian port to gain control of a nuclear submarine. Price uses the submarine to launch a submarine-launched ballistic missile towards Washington D.C. He sets the warhead to detonate in the upper atmosphere, which unintentionally destroys the International Space Station and creates an electromagnetic pulse that cripples vehicles and electronic equipment on both sides, giving the Americans an advantage. Back on the ground, Foley and his squad seek shelter from the disabled aircraft that are now literally falling from the sky, and proceed to the White House. There, they receive a transmission informing them that the Air Force is preparing to carpet bomb the entire city to deny the Russians a strong foothold. Foley’s squad fight their way to the roof of the White House and set off green-colored flares, aborting the air strike with less than thirty seconds to spare. Flares are lit on the rooftops of other landmarks, signifying that the city is in American hands.
Narrowing down Makarov’s hiding place to two separate locations, Task Force 141 decides to split up. Price and Soap travel to an aircraft boneyard in Afghanistan, while Roach and Ghost raid Makarov’s safe house on the Georgian-Russian border. At the safe house, Roach and his team obtain vital intelligence from Makarov’s computer and escape with Makarov’s men in pursuit. However, when they reach the extraction point, Shepherd betrays and kills them, retrieving the intelligence and taking it with him. Price and Soap quickly learn of Shepherd’s betrayal and escape a battle between Shepherd and Makarov’s men with the help of Nikolai. Price contacts Makarov on an open radio channel and makes a deal to kill Shepherd, with Makarov grudgingly revealing the location of Shepherd’s mountain base in Afghanistan. Price and Soap raid the base in an attempt to take revenge on Shepherd in a suicide mission. During the infiltration, Shepherd destroys the base using the self destruct system then tries to escape and a boat pursuit ensues.
At the climax of the pursuit, Shepherd boards a helicopter, only for Price to disable it by shooting the helicopter’s rotor, causing it to crash. Price and Soap tumble over a waterfall in the process. After recovering from the fall, a dazed Soap follows Shepherd and attempts to kill him. Shepherd slams Soap into a rusted car, stabs him in the chest and prepares to kill him with his revolver. Just before he can, Price attacks Shepherd and the two engage in a hand to hand fight, with Shepherd slowly gaining the upper hand. Soap manages to pull the knife from his chest and throws it at Shepherd, piercing his left eye and killing him. Price bandages Soap’s wounds as Nikolai arrives in a helicopter to extract them, having gone against Price’s advice not to return for him and Soap. Nikolai warns them that they will be pursued, but Price insists that Soap receive medical attention. Nikolai mentions that he knows a safe place to go to.