For anyone wanting to get some sneak peaks at the story of Halo 4, I would recommend the various Halo based novels. I enjoyed all of them, but the ones that directly relate to Halo 4 essentially draw a path from Halo: Combat evolved to the events leading up to Halo 4. These books start with Halo: First Strike by Eric Nylund, which takes place just after Halo Combat evolved and explains how the Master Chief returns to Earth for the beginning of Halo 2, but diverts to some other events that ultimately lead to Halo 4. The next novel in the sequence is Halo: Ghosts of Onyx also by Eric Nylund, which continues the sequence of events which began in First Strike. the next two novels are Halo:Glasslands and Halo:The Thursday War both by Karen Traviss, and these two are part of a currently unfinished trilogy, and the trilogy leads directly to Halo 4.