With the ranks of Spartans depleted from war with the Covenant, Muso-096 oversees the new Spartan-IV program as separate branch of armed service. Sarah Palmer is among the first wave of new Spartans.
Master Chief is reunited with his old squad Blue Team and leads them to a Halo research station to investigate the disappearance of Spartan Team Black.
Master Chief [John-117] (flashback); the Librarian (flashback); Dr. Catherine Halsey; Prometheans; Sarah Palmer; Thomas Lasky; Gabriel Thorne; Roland; Jul'Mdama