In the year 2552, humans on the planet Madrigal have been fighting for independence from Earth, but a fatal encounter with the Alien Covenant complicates things. Master Chief John 117 and his super-soldier “Spartans” join the fight. After the battle, Master Chief heads to his home planet of Reach with a Madrigal survivor and a mysterious object he discovered on the planet. But a controversial order has John questioning his mission, and himself.

John seeks revenge on a secret ONI planet. Perez trains to become a new kind of soldier. Kai finds herself torn between her Spartan code and her loyalty to Master Chief. Makee turns to Cortana for help in her search for the Halo.

John-117 comes face to face with Makee. A revelation leads Ackerson to question his loyalties. Soren and Laera's relationship begins to fracture. Halsey, Kwan and Miranda work to solve a mystery.