The single-player mode in Call of Duty: Modern Warfare consists of 14 high-action missions, ranging in setting. Below, you'll find a list of them all and their respective walkthroughs: Fog of War.
Fortunately, the first-person shooter genre is not known for its lengthy campaigns, with CoD game story modes typically lasting under 10 hours (depending on your skill level). You should have no trouble fitting this game's singleplayer in if you're keen on seeing what happens in the direct sequel to 2024's MW2.