According to a scene that made its way onto Twitch, the newest Halo character will be looking for the series' flagship Spartan. He's getting help from Master Chief's enemy/ally, too.
In what looks to be a part of the The Master Chief Collection's additions meant to connect previous games to Halo 5 , a cutscene has Locke in a tense conversation with the Arbiter and other Covenant characters. Locke seems to be on the hunt for Master Chief and seems to be trying to enlist the Covenant's aid. The scene supposedly leaked during a Twitch streamer's broadcast of the game when he selected Halo 2 Anniversary's "The Heretic" campaign map.