Shepherd sends Allen on an undercover mission in Russia in order to get close to Makarov. Allen joins Makarov in a brutal massacre of unarmed civilians waiting in a terminal at fictional Zakhaev International Airport in Moscow. Makarov, however, is apparently wise to the fact that Allen is undercover. He kills Allen, exposes his identity as an American, and turns him into a scapegoat for the brutal terrorist attack.

Angered by what they believe is an American-supported terrorist attack, Russia stages a massive surprise invasion of the United States. It turns out that the ACS module recovered earlier by Task Force 141 has already been cracked, which allows the Russian forces to advance without alerting the U.S. until they are very close. Private James Ramirez and his squad of U.S. Army Rangers, led by Sergeant Foley, are called upon to defend a Virginia suburb from the Russian attack.

Meanwhile, Task Force 141 work on tracking down Makarov. Intelligence from the airport attacks lead them to Rio de Janeiro to investigate leads on Makarov's contacts, but the only intelligence they learn from the operation is that the most hated enemy of Makarov is locked up in a Russian gulag. As a result, Soap decides to rescue the prisoner from the gulag to use him as a bait to draw Makarov out. With assistance from the Navy SEALS and U.S. Marines, Task Force 141 manages to free the prisoner, who is revealed to be Captain Price. Price agrees to help them track down Makarov, but knows they must go to extremes to end the war. He decides to go rogue, hijack a Russian nuclear submarine, and launch an ICBM towards Washington, D.C. However, he rigs the warhead to explode in the upper atmosphere, which destroys the International Space Station (viewed from an astronaut's point of view), but spares Washington. The resulting electromagnetic pulse cripples the vehicles and electronic equipment of both the U.S. and Russian forces in the city. Later, Ramirez and his squad discover that the Air Force has assumed that D.C. has been lost after the nuclear explosion and plans to carpet bomb the city. The only way to abort the operation is to set off green flares on the roof of the White House, which is under Russian control. Ramirez and his squad fight their way to the roof the building and manage to set off their flares in the nick of time, while green flares on the roofs of other D.C. landmarks signify that the city remains firmly in American hands.

Narrowing down Makarov's hiding place to two separate locations, Task Force 141 decides to split up. Price and Soap go to the aircraft boneyards in Afghanistan, while Roach and Ghost raid Makarov's safehouse in the Caucasus Mountains. The latter obtain vital intelligence that implicates Makarov in the massacre at Zakhaev International Airport. However, General Shepherd betrays them and kills both Ghost and Roach. It is revealed that Shepherd intends to take advantage of the global crisis to turn himself into a global hero. Price and Soap quickly learn of Roach and Ghost's death and manage to escape Shepherd's ambush with the help of Nikolai. After learning the location of Shepherd's secret base in Afghanistan from Makarov, they decide to take revenge on him in one final, bloody suicide mission. However, during the infiltration, Shepherd tries to escape and a long boat pursuit ensues.

Shepherd appears to escape when he drives his boat into the back of a hovering MH-53 helicopter. However, Price manages to shoot down the helicopter just before their boat tumbles over a waterfall. After recovering from the fall, an injured Soap staggers after Shepherd and attempts to kill him with his knife, but Shepard blocks the attack and stabs Soap with his own knife. As Soap lays on the ground, Shepard pulls out his pistol and prepares to execute Soap, but before he can, Price attacks him and knocks the pistol away. Price and Shepard then engage in an extended fist fight. Soap meanwhile, attempts to crawl towards Shepard's pistol, but Shepard kicks it away before he can grab it. Soap then pulls the knife out of his own chest and throws it at Shepherd, striking him in the eye and killing him. Price attends to Soap's wound before Nikolai arrives in a helicopter to extract them. Price warns Nikolai that they will be international criminals for what they've done, and they agree that they should go into hiding.

Activision announced that its own estimates have the game's cumulative sales total breaking the $1 billion mark in just two months on shelves.

In 2007, Infinity Ward rebooted the World War II-centric series it created with its contemporary-set Modern Warfare, a game that has now sold more than 14 million units.

Wtf? Price is good guy, but launches a nuclear missile at DC?

The story is not for the intelligent people.