At an elementary school in Ukraine, Ghost is shown taken hostage (Along with several school children) by terrorists who demand that a ransom be delivered to the school in a span of three hours. If the ransom is not delivered before the deadline, the terrorists plan on killing one child every minute.During this time, Ghost tells the story of one Lieutenant Simon Riley, who is on a joint operation with U.S. Special Forces to eliminate a drug cartel leader named Roba in Mexico.
Riley and the American operatives parachute into Mexico during Día de los Muertos (Day of the Dead), however after they land, Riley and the team finds out that one of their fellow special ops members fell to his death after his parachute failed to deploy.
Riley suspects that this wasn't an accident and believes there is someone in the team who is under Roba, but decides not to discuss it with the team as it might get him and the others killed.
The team continues on with the operation and they manage to infiltrate a Day of the Dead party Roba is throwing, but soon the rat in the team reveals himself and the entire operation is compromised.
Riley attempts to flee the scene but Roba shoots him an soon after he is captured along with the rest of the team.
The entire team is brutally tortured for several days in order to brainwash them and have them work for Roba. During this time, Riley experiences flashbacks from his youth and early military days, about how he dealt with his abusive father, his drug addicted brother and grief-stricken mother.
Shortly thereafter, two of the team's members, Sparks and Washington escape from Roba's men but Riley is left behind. Soon Roba orders that Riley be thrown into a ditch with one of the team's members.
Riley is buried alive with Lieutenant Vernon, who is dead and now decomposing. Riley uses his jaw to dig his way out, and is barely able to reach Texas, where a local sheriff finds him.
Riley is sent back to the U.K. to be debriefed, and while the S.A.S finds him to be physically fit for combat, they doubt that his mental condition is stable as he has nightmares about Roba attempting to kill him.
In the end, the high command orders that Riley see Major Hawkins, the S.A.S psychiatrist, and is left out of future special ops missions.
On Christmas Day 2010, Riley is with his brother and sister-in-law along with his mother when Sparks, one of the members from the Mexico operation, visits him. Sparks takes Riley to a pub where they have a few drinks and share stories from the operation.
Afterwards they leave the bar and Sparks spots a gorgeous blonde down the street and tries to hit on her, but when she isn't so interested in him Sparks knocks her out. Riley secretly calls the police and tells Sparks not to do any more harm to the woman. He agrees with Riley and they both head to Sparks hotel room.
Riley suspects something is going on with Sparks, who shortly pulls a gun to Riley's head but Riley knocks the gun away and questions Sparks. He reveals that he and Lt. Washington have been working for Roba, but before Riley continues interrogating him, Washington arrives and Riley is forced to flee.
Riley heads back home but finds that his brother, his sister-in-law and mother have been murdered. Riley suffers a panic attack from this, and in the process goes to the office of Major Hawkins and strangles her.
Sparks and Washington track down Riley, who is still at the office of Hawkins, and Washington fires a grenade round into the office. Riley escapes, but decides to meet up with his terminally ill father at the hospital to tell him that his wife and kid have been murdered.
Both of them talk about their pasts, and in the end Riley leaves and remains bitter towards his father, while his father feels the same way about him.
Shortly after he leaves the hospital, Sparks and Washington arrive at the hospital in an attempt to receive information on Riley's whereabouts. Riley's father is interrogated but doesn't comply. In the end Sparks and Washington shoot him.
Riley now plots to kill Sparks and Washington, and when he finds Sparks he binds and gags him before eventually setting his house on fire. Shortly afterwards Riley sneaks into an airbase and slits the throat of Lieutenant Washington.
After killing the two American soldiers, Riley assumes the title 'Ghost' and hears that two former military men were ambushed and killed in Mexico. Suspecting that the ones who did this may have a lead on Roba, Ghost tracks them down and interrogates the leader, who reveals that Roba is hiding in his summer home in a remote location.
Ghost heads to Chiapas, where he infiltrates Roba's home and after a fierce shootout, Ghost manages to kill him by shooting him in the head.
Back at the Ukrainian school, the deadline has been reached and the terrorists are trying to figure out why there aren't any troops attempting to rescue the children. Ghost reveals that they were waiting for his signal and soon soldiers break into the windows and eliminate the hostiles.
One of the terrorists holds a little girl hostage, and Ghost tries to get him to let her go or else he will be shot. The terrorist doesn't comply and a sniper onboard a helicopter shoots him in the head.
In the end, a flashback is shown of Ghost walking away from Roba's destroyed summer home and a helicopter lands to pick him up. A soldier steps out and the patch of Task Force 141 is shown, meaning that Ghost has been admitted into the elite multinational force.
Task Force 141
After being admitted into TF-141, Ghost is teamed up with S.A.S Captain, John MacTavish. After an undercover C.I.A agent is killed while taking part in a massacre of hundreds of Russian civilians (The agent was attempting to acquire information on a terrorist cell, but the terrorist leader, Makarov, found out he was working undercover and killed him.) Russia declares war on the United States.TF-141 commander General Shepherd wants to prove to the Russians that the U.S. is not responsible, but can't do it without finding several leads first.
Shepherd sends Ghost along with TF-141 members John 'Soap' MacTavish and Gary 'Roach' Sanderson to Rio De Janeiro to find Alejandro Rojas, who has been supplying arms for Makarov's men.
The three fight their way through fierce opposition in the slums of Rio to capture Rojas and are successful. Rojas reveals that one person has become one of Makarov's worst enemies, and that he might be the key to finding Makarov.
Soap, Ghost and Roach escape Rio, and begin their hunt for what they know is "Prisoner #627". #627 is locked up in a Russian gulag. Before initiating an attack on the gulag, TF-141 eliminate Russian anti-aircraft batteries stationed on oil rigs.
As the oil workers are being held hostage by the Russians, Shepherd orders that TF-141 lead by Soap, Ghost and Roach, eliminate the Russian troops and rescue the hostages.
TF-141 is successful and the operation to rescue Prisoner 627 is given the green light.Ghost provides support during the operation by using the gulag's security cameras to alert Soap and Roach of the gulag's guards, as well as lead them to Prisoner 627, who is actually Soap's former commander Captain Price.
After narrowly escaping the collapsing gulag, Price insists that TF-141 infiltrate a Russian submarine base. Shepherd complies and they successfully enter the base, but to everyone's surprise Price uses a nuclear sub to launch a ballistic missile to Washington D.C., where a battle between the Russians and Americans.
The missile, carrying an electromagnetic pulse warhead explodes over D.C., knocking out electronics but giving the American soldiers a slight advantage.
Ghost's final op begins in Caucasus Mountains, where Makarov's safehouse is located. Ghost and Roach lead a squad of men into the well-fortified safehouse, filled with landmines and heavily armed men.
They manage to rid the house of enemies and while Makarov is not present, they go for the next best thing, which is his computer. Roach attempts to extract Makarov's files while Ghost fends off Makarov's men. Roach successfully retrieves the vital intelligence and both of them exit the house and make a run for their rescue helicopter.
As enemy mortar fire rains down on the two soldiers, one shell lands near Roach and severely wounds him, and Ghost is forced to pull him towards the rescue helicopter where TF-141 commander General Shepherd is waiting.
Shepherd asks if they have retrieved the files. Ghost confirms it and continues helping Roach to the helicopter.
However Shepherd, distressed after losing 30,000 men in a nuclear strike five years ago, wants to make it look like he was the one responsible for retrieving the intelligence so he betrays them and shoots Roach with his revolver. Ghost experiences the same fate and is shot in the chest, unable to react quickly.
Soon after, several U.S troops dump them in a ditch and soak them with gasoline, before Shepherd dramatically flicks his cigarette into the ditch and lights the fire, killing both of them.