A hostile moon on which Tilly, Adira and a group of quarrelsome Starfleet Academy cadets crash in 3190 and must work together to survive predatory creatures.
Kokytos is a moon seen in the Discovery fourth-season episode All Is Possible. Sylvia Tilly, accompanied by Adira Tal, takes a small group of Academy cadets on what is meant to be a simple team-building flight, but a gamma-ray burst knocks their shuttle off course and it crashes on the frozen surface, killing the pilot.
The cadets, who come from worlds only recently reunited after the Burn, distrust one another, and the wreck's power draws luminous predators that feed on energy. With communications blocked, Tilly leads the group on foot to high ground where a signal can get through, using the journey to make them listen to each other.
The party is picked up by the USS Armstrong. The experience convinces Tilly that teaching is her calling, and at the end of the episode she accepts Kovich's offer of a post at the Academy and leaves Discovery.