Halo: The Gray Team Books in Order

In the early Human-Covenant War, the UNSC’s Cole Protocol requires dangerous navigation data to be erased before it exposes Earth. Lieutenant Jacob Keyes, Gray Team, refugees in the asteroid settlement called the Rubble, and Covenant rivals are drawn into a struggle around Hesiod.

On Carrow, human colonists and Sangheili settlers face renewed violence after years of uneasy coexistence. Peace envoy Melody Azikiwe must also free Gray Team from an Elite fleetmaster, while the escalating conflict exposes an ancient danger beneath the planet.