Halo 4 takes place 4 years after Halo 3. Master Chief is asleep in a cryopod in what’s left of the ship Forward Unto Dawn. Cortana wakes him up because a Covenant group of salvagers boarded the ship. The ship had floated through space to a Forunner (an ancient civilization that had collapsed and died out) shield world (a built planet). Out of the planet came a large orb. In the orb was one of the last Forunners called the Didact. You have to stop him from getting to Earth. Halo 4 came out in 2012 on the Xbox 360.
All About Halo 