The singleplayer campaign features many elements from past installments, taking place in numerous locations across the world. Levels are now built in sandbox-style environments, allowing players more freedom to complete objectives. Players can now spot enemy targets to notify the AI of Tombstone squad. The singleplayer also features three separate endings based on the player’s choice in the final mission.
The singleplayer features assignments that require specific actions and unlock weapons for use in multiplayer upon completion. Collectible Weapons return along with the introduction of Collectible Dog Tags which can be used in multiplayer. Weapon crates are found throughout all levels, allowing players to obtain ammo and switch weapons. While crates hold default weapons, collectible weapons may be used whenever they are acquired and level specific weapons may be used once a specific mission assignment has been completed by obtaining enough points in a level.
The singleplayer campaign is set in the year 2020, six years after the events of the previous game. While the War of 2014 has ended, tensions between the United States and Russia are at an all-time high. Meanwhile, Admiral Chang, the main antagonist, looks to overthrow the Chinese government by blaming the United States for the assassination of Jin Jié, the country's future leader and voice of peace. If successful, China would gain Russia's full support, resulting in all-out war with the United States.
The player controls Sgt. Daniel Recker, a member of a United States special operations squad call-signed Tombstone. His squadmates include: squad leader SSgt. William Dunn, second-in-command SSgt. Kimble 'Irish' Graves, and field medic Sgt. Clayton 'Pac' Pakowski. Tombstone is joined by CIA operative Laszlo Kovic, and Chinese Secret Service agent Huang 'Hannah' Shuyi. They are tasked with stopping Chang and preventing another great war.
Tombstone was tasked with retrieving vital information in Baku, Azerbaijan. Pursued by Russian Special Forces, the squad engaged in numerous firefights as they proceeded toward the extraction point at the top skyscraper under construction. The building, after sustaining massive amounts of damage from Russian forces, collapsed as Tombstone reached the extraction point. The event resulted in the helicopter's destruction as well as the amputation of Dunn's leg due to it being trapped under rubble.
Stranded, Tombstone commandeered a civilian vehicle and attempted to escape with an enemy helicopter in pursuit. Recker was then tasked with destroying the chopper with a grenade launcher. While successful, the squad's vehicle went off road and plunged into the sea. With the vehicle sinking, Dunn, who was not only trapped between seats but also critically wounded, handed Recker his revolver and ordered he shoot out the windshield so the rest of the squad could make their escape. Much to the dismay of Pac and Irish, Recker reluctantly shoots the window, allowing them to escape but resulting in Dunn's death by drowning.
The Intel recovered tells that Admiral Chang is planning a military coup d'état in China which would allow him to gain full Russian support if successful. Unfortunately, Captain Garrison's superior, Oracle, reveals that the United States had already known this information and that the purpose of Tombstones mission was to reassure them of it, meaning that Dunn had died for information that they already knew.
Tombstone returns to the USS Valkyrie where Garrison informs them of the assassination of Chinese presidential candidate, Jin Jié; and how Chang convinced the Chinese that the United States was responsible. He then sends Tombstone on a covert mission to Shanghai to rescue three VIPs: CIA Agent Kovic, Hannah, and Hannah's husband. Full filling Dunn's last wish, Recker is made squad leader of Tombstone.
Tombstone manages to extract the three via helicopter and then proceeds to take a tourist boat back to the Valkyrie. Much to their surprise, however, an electromagnetic pulse goes off, frying all electronic equipment in the area, including the boat. Realizing that other refugees are stranded on boats around them, Irish helps to lead them to the Valkyrie.
Once aboard, Captain Garrison sets a course for the USS Titan which will be able to house the refugees. Upon locating the Titan, it is found to be heavily damaged by Chang's Chinese military. Garrison thereby orders Tombstone, along with Kovic as acting squad leader, to scour the wreckage of the Titan for survivors and Intel before it sinks.
The squad recovers a hard drive with data telling of what happened before the Titan was attacked only to be forced to engage with Chinese soldiers that had boarded the ship. Having sustained too much damage, the Titan finally buckles under its own weight and splits in two forcing Tombstone to abandon ship. Having hijacked an assault boat, the squad makes its way back to the Valkyrie only to find it under siege by Chinese forces.
Kovic is critically injured as the squad attempts to repel Chinese forces, resulting in Recker being put back in charge of Tombstone before he dies. Tombstone then clears the bridge and rescues Garrison and Hannah's husband.
Garrison debriefs the squad on the incoming assault on the Chinese-controlled Singapore airfield to destroy Chinese air superiority while their air forces are grounded by a storm. Hannah volunteers to join Tombstone, much to Irish's chagrin. They successfully assault the beach and lead an advance towards the airfield, with the help of US Marine tanks, losing most of their forces in the process. While crossing a bridge to the airfield, Recker becomes pinned down by a car blown by the strong winds and tries to break free with the help of Tombstone, to no avail. A large freighter crashes into the bridge, throwing Tombstone into the sea below.
Fortunately, they survive and make their way to the airfield via a sewer. After Pac fires the signal flare, Tombstone attempts to evacuate the area using an enemy vehicle, but is hit by friendly fire, seemingly killing Pac and rendering Recker and Irish unconscious. Hannah betrays the squad, bringing Chinese soldiers to capture Tombstone. Recker and Irish are interrogated in a prison by Admiral Chang and Bohai over the purpose of their mission in Shanghai. They are then thrown into prison cells soon after.
Recker is later awoken by Dimitri Mayakovsky, a Russian prisoner suffering from radiation poisoning as a result of the nuclear explosion in Paris six years prior. The two break out of their cell and release the other prisoners, including Irish, starting a mass riot. With the prison guard overrun, the Chinese military arrive and launch an assault.
Recker and Irish hold them off long enough for Dima to open the prison gates, only to be caught by Hannah and other soldiers. Hannah shoots the soldiers holding Recker, Irish and Dima at gunpoint; she explains that she had been tasked to protect Jin Jié, who had been posing as her husband. The group fights their way through the Kunlun Mountains to a cable car, which goes down the mountain. The tram is shot down by an enemy helicopter, resulting in Dima's death.
Forced to continue on foot for two days, Tombstone makes their way down the mountain, forced to hunt for food to survive. They find a jeep and drive to Tashgar, finding it under siege by both Chinese and Russian forces. They eventually find Major Greenland, who commands the remainder of US ground forces in Tashgar. She states that the mobile anti-air control by the Russians is putting them at a disadvantage.
Tombstone volunteers to demolish the Tashgar Dam to flood the area and destroy the Chinese-Russian forces in exchange for a ride back to the Valkyrie. They are successful in their task and are sent to Suez Canal to await extraction back to the Valkyrie.
They are picked up by a C-130 using the Fulton surface-to-air recovery system, and are then paradropped onto the Valkyrie, which is sailing blindly into Admiral Chang's forces. Tombstone assists in clearing the deck of boarding Chinese forces and find Garrison, who is holed up with Jin Jié, other survivors, and Pac (who had survived Singapore by "crawling through a thousand yards of shit with a hole in his stomach").
When Chinese forces finally reach the door to the medical bay, Jin Jié convinces Garrison to let him show his face to the soldiers, as they had been fighting under the illusion that Jin Jié had been killed. Recker opens the door and is knocked down, but Jin Jié calms the tension between the three forces showing his face to them, ultimately signifying an alliance and friendship between the United States, Russia, and China. The Chinese soldiers celebrate the news of their leaders return and call off the attack and inform the Russians and convince them to change sides in the war.
However, upon hearing this news, Chang barrages the Valkyrie with his warship, hoping to "bury the truth" with it. With no ordinance to strike back, Recker, Irish and Hannah once again volunteer to manually destroy it with explosives. Driving a boat to the warship's blind spot, the trio set the remote charges and use grappling guns to bring them to safety before detonating the explosives.
Unfortunately, the remote detonation fails, requiring manual replacement of the charges. Hannah volunteers to set a new charge; but Irish stops her, volunteering to do it himself, as China would need her. Recker is forced to either do nothing as Chang's warship obliterates the Valkyrie, thus killing Pac, Garrison and Jin Jié; or to send either Hannah or Irish back down to set the explosives. As soon as the detonator lights green, Recker detonates the charges, destroying Chang's ship but killing whoever planted the explosive.
A Marine rescue helicopter then picks up Recker and his remaining teammate, reporting to Garrison that one member could not be found. During the credits, the player hears a new dialogue between Irish and Hannah, discussing their pasts, and how they have to keep moving forward with "no fucking regrets", implying that the teammate that went down may have survived.