Here you can find the Call of Duty 4 storyline.
A Russian nationalist by the name of Imran Zakhaev is set on returning his homeland to the Soviet times. Volkov knows the United States would never allow this to happen, thus he funds a coup in the Middle East, organized by his ally Al-Asad, to draw attention away from Russia. The two men and their seconds-in-command gain the nickname The Four Horsemen. However, the British and US governments have been monitoring Volkov's activities and discover his real intentions. The story is told from a perspective of a British 22nd SAS Regiment operative in Russia and American 1st Force Recon in the Middle East.
The game also features a flashback mission set 15 years ago in the Chernobyl Zone of Alienation, which features a new incarnation of Captain Price from 22nd SAS Regiment, the only character to appear in both of the first two games of the Call of Duty series. He needs to assassinate Volkov, but his mission fails because his Captain gets wounded and he has to get out him of the Zone of Alienation. Whether this new Price will be confirmed to be a relative of the WWII era Price remains to be seen. It is also believed that the assasination attempt left Volkov with only one arm.
The game features the following as playable characters:
- Lieutenant Price, 22nd SAS Regiment (15 years ago)
- Sergeant John 'Soap' MacTavish, 22nd SAS Regiment (present)
- Sergeant Paul Jackson, 1st Battalion, 7th Marine Regiment (later Sergeant as part of 1st Force Recon Co., U.S.M.C.) (present)
The game features the following as unplayable characters:
- Captain MacMillan, 22nd SAS Regiment (15 years ago)
- Captain Price, 22nd SAS Regiment (serving as MacTavish's commanding officer. Uses the same model as Call of Duty and Call of Duty 2 incarnation) (present)
- Lieutenant Vasquez, 1st Force Recon Co., U.S.M.C. (Sgt. Paul Jackson's Platoon Leader) (present)
- Sergeant Griggs, 1st Force Recon Co., U.S.M.C. (Support Gunner of Sgt. Paul Jackson's Squad) (present)