Operation Purgepoint is a mission, you play as a member of STS6 or Strike Team Six, you are a mercenary peackeeping squad of Freelancers the best of the best hired by the UNSC to stop a covenant fascist group that has convinced some of humanity to fight for them, they are called The Dred or Dredsmen. They seek an index, a purger of any desired species, so you must stop them and finish the fight.