Nikolai evacuate a dying John "Soap" MacTavish from Site Hotel Bravo, Afghanistan. They reach a safehouse run by Nikolais Loyalist allies in Himachal Pradesh, India. While Soap receives medical attention, Vladamir Makarov's forces storm the safehouse in an attempt to kill the three. Yuri, Nikolai's best soldier with a grudge against Makarov, aids Price in giving Soap an adrenaline shot to keep his heart going, and with securing a safe route to an extraction point out of the country. Together, the four are all that remains of the now-disavowed Task Force 141. Price's team then goes into hiding for two months, while Makarov does the same.
On the same day, World War III continues. The actions of Delta Force Team Metal, which includes Sgt. Derek "Frost" Westbrook, "Grinch", "Truck", and their C.O. "Sandman" (with whom Soap, Price, and Ghost previously worked together with on Operation Kingfish three years ago to kill/capture Makarov), facilitates the Russian army's withdrawal from the invasion of Lower Manhattan, New York. They start by destroying a jamming tower on top of the New York Stock Exchange, then with hijacking a Russian Oscar II submarine in the East River, in order to use its ordinance against its own fleet.
On October 4th, 2016, Russian President Boris Vorshevsky announces plans to make peace with the United States at a summit in Hamburg, Germany. However, the plan is derailed when Makarov's men hijack Vorshevsky's plane and force it into a crash landing at the airport. F.S.O. Agent Andrei Harkov attempts to secure Vorshevsky's safety, but is killed when Makarov appears inside what the F.S.O. mistake as the evac chopper. Makarov kidnaps the President, and plans to capture and torture his daughter, Alena, to force the President to give Makarov the launch codes for the Russian nuclear arsenal.
Soap eventually recovers enough to fight, and with help from Yuri, and from Price's former mentor and C.O., MacMillan, they follow Makarov's trail to an arms transport in Sierra Leone, but are unable to intercept the cargo. This cargo of unknown nature is distributed to Paris, Berlin, and London. Meanwhile, a British S.A.S. unit, including Sgt. Marcus Burns and Sgt. Wallcroft, is sent in to deal with the cargo, but discover one of the transports to be a decoy. Meanwhile, a piece of the real cargo, revealed to be a biochemical weapon from Fregata Industries, is detonated on a London street nearby, killing a young American family as it releases its toxic payload near Big Ben.
The chemical attacks pave the way for the Russian Army to invade Europe, and Team Metal is deployed to Hamburg to rescue the U.S. Vice President from a hostage situation. Acting on intelligence supplied by Price, who had extraced it from a warlord in Somalia named Waraabe, they are later deployed to Paris in order to capture Russian bomb-maker "Volk", the apparent CEO of Fregata. After securing Volk, they fight their way through the city to an extraction point with the help of an AC-130 gunship; however, the Eiffel Tower collapses into the river after a bombing run eliminates all Russian forces at the escape point.
After extracting information from Volk, Team Metal learns of Makarov's current location: the Hotel Lustig (loosely based on the Four Seasons Hotel) in Prague, where Makarov is about to call a meeting with his top advisors. Sandman informs Price of this information, and Price's team infiltrates the locked-down city. Once in Prague, Task Force 141 meets up with Loyalist Kamarov, now one of the organizers of the local Czech Resistance, to try to assassinate Makarov. Yuri and Soap take sniping positions from a church tower across from the hotel, while Price sneaks into the building itself. However, the plan goes awry when Kamarov himself is taken hostage and rigged with explosives. Price escapes the hotel just as Kamarov is blown up. Makarov reveals that he knows Yuri personally, by acknowledging him as his "friend". Makarov had already predicted Yuri and Soap's overwatch spot and had it rigged with explosives, which he then detonates.
Yuri and Soap avoid the explosion by jumping down to ground level, but Soap is mortally wounded due to the height he fell from the tower and a large chuck of debris falling on him, the force of the ordeal causing his knife wound to reopen. Yuri helps Soap and escapes with Price to a resistance safehouse. In his last moments, Soap tells Price about Makarov's knowledge of Yuri before dying. After leaving his M1911 pistol with Soap's body and taking Soap's journal and dog tag, an enraged Price punches Yuri down a staircase and holds him at gunpoint, demanding him to explain his connection with Makarov.
Yuri explains that he was a former Ultranationalist who befriended Makarov, and was responsible for escorting Makarov and Zakhaev. He was present with Makarov at Prices assassination mission in 1996, evacuating Zakhaev from the arms deal. Yuri was also with Makarov when the latter detonated the nuclear bomb in the Middle East, killing 30,000 of Shepherd's Marines. After witnessing the nuclear explosion, and Makarov's reaction, Yuri attempted to stop the massacre at the Zakhaev International Airport in Moscow 5 years later by attempting to alert the F.S.B. there. However, Yuri was found out, and was restrained and shot in the stomach by Makarov himself before the attack started. Yuri's guilt of being unable to prevent the mass murder convinces Price that they are fighting for the same thing, and Price decides to keep his alliance with Yuri.
After infiltrating Makarov's castle near Prague and learning of Vorshevskys captivity, Price and Yuri alert Team Metal of an Ultranationalist plan to abduct Alena from a safehouse in Berlin. Team Metal is unable to prevent the kidnapping, but they are able to trace Makarov's Ultranationalists to a Siberian diamond mine. Team Metal (without the inclusion of Frost) and Task Force 141 launch a joint-rescue operation to save the Vorshevskys before Makarov gains the launch codes. Their actions ensure the safety of President Vorshevsky and Alena, and end the conflict between the United States and Russia. During extraction, Sandman, Grinch, and Truck stay behind to buy the evac chopper some time, and are assumed KIA when the mine collapses on them.
On January 21st, 2017, 3 months after the end of World War III, Price, Yuri, and Nikolai track Makarov to the Hotel Oasis (loosely based on the Burj Al Arab in Dubai), in the Arabian Peninsula. They assault the hotel, with Price and Yuri wearing E.O.D. armor, which is later destroyed. On the hotel roof, Makarov attempts to escape on a helicopter, but Price jumps on, killing the two pilots and crashing the helicopter back onto the roof. A dazed Makarov prepares to execute an equally injured Price, but is distracted by Yuri, killing him instead. Enraged with the loss of another ally, Price takes advantage of the moment to tackle Makarov, wrapping a steel cable around his throat into a noose before breaking through the glass roof, resulting in Makarov's death by hanging. Price lands on the atrium floor just below and survives. As the police arrive on the scene, Price sits up in front of Makarovs hanging corpse and quietly smokes a cigar[/b].

The entire Killstreak reward system has been revamped. Killstreaks are now known as Pointstreaks, and kills are no longer the only way to increase the player's pointstreak. Completing objectives such as planting the bomb in Search and Destroy or capturing a flag in Capture The Flag awards points towards the player's Pointstreak. Pointstreak rewards are organized into three different "strike packages" called Assault, Support, and Specialist. The Assault strike package works the same as the Killstreak reward system in Modern Warfare 2 and Black Ops, offering rewards like the Predator drone and attack helicopters. The Support strike package offers support-style rewards, such as UAVs and SAM Turrets. Rewards from the Support category do not reset when the player dies, but accumulate over the course of a match. The Specialist strike package rewards players with perks of their choosing after every second consecutive kill. After eight kills, they receive every perk in the game, but reset back to none upon death.[17] Players are allowed to choose which Pointstreak rewards they want to use when they gain it during the match, rather than choosing them between rounds.
Along with revamping the entire Killstreak reward system, Modern Warfare 3 also has a completely modified Ranking and Unlocks system, which does not use a currency system for unlocks.[18] The player's primary weapon levels up alongside the player, and unlocks a number of "Proficiency" perks such as Attachments, (allows two attachments and is a successor to the "Bling" and "Warlord" perks), Kick (reduced recoil while aiming down the player's sight) and Focus (reduced flinching while under fire). Only one Proficiency can be put on a primary weapon.[19] Another new addition is the ability to equip "Hybrid Scopes" on a weapon, such as a Reflex Sight and a magnifier similar to an ACOG on the same weapon, and the player can switch between the scopes.[19] Modern Warfare 3 introduces a new "Prestige Shop" which will unlock only after the player has selected the option to prestige for the first time. The "Prestige Shop" allows Prestige players to use tokens they gain from using the Prestige option to buy exclusive features such as double XP and an extra custom weapon class.[20]
Several controversial perks in Modern Warfare 2, accused of being overpowered, have been removed in Modern Warfare 3. Diving from standing to prone, known as "dolphin diving", has been removed due to balancing issues.[21] Modern Warfare 3 will utilize Treyarch's hot fix system to fix bugs and glitches.[22] Modern Warfare 3 features a local and online split-screen option.[23]
Several new game modes have also been added:
"Kill Confirmed" requires players to collect floating dog tags from the corpse of a downed enemy before the kill can be registered. However, the opposing team can pick up the dog tag as well to deny the other team of a kill.
"Team Defender" requires both teams to try to capture a flag dropped by the first person who gets killed when the match starts, and hold it to gain double points per kill while the team without the flag only gets the default amount per kill.
Private matches also now include pre-made game modes including: "Infection" (where the infected kills enemies to recruit them to their team), "Drop Zone" (where the player must hold a drop zone for points and care packages), "Team Juggernaut" (each team plays alongside an AI Juggernaut character), "Gun Game" (be the first to get one kill with every gun in the game) and "One in the Chamber" (in which players are only allowed one pistol with one bullet and three lives where they can only get more bullets by killing other players). Along with this, players are allowed to create their own game modes with customized settings such as number of players and time limit.[17]

Call of Duty: Elite is a new free/subscription-based service developed by Beachhead Studios for the multiplayer portion of Modern Warfare 3 (as well as the previous installment in the series, Black Ops). It was first showcased at E3 2011 and was released on November 8th, 2011 to coincide with the release of Modern Warfare 3. The free version includes features such as lifetime statistics and social-networking integration. The subscription version is priced at $49.99 per year and includes monthly downloadable content, daily competitions with virtual and real life prizes, the ability to level up your clan, pro analysis and strategies, and more.