Under the Twin Moons

Following his actions on Q'mau, Rayner is brought before a disciplinary hearing by Federation president Laira Rillak who believes that Rayner's recklessness is not suitable for Starfleet in peacetime. Using images of the journal that they retrieved from Fred's memory, Burnham and Discovery travel to the uninhabited burial planet of Lyrek where they believe the Progenitor technology, or a clue to it, is hidden. Burnham and her first officer Saru—on his last mission with Discovery before becoming a Federation ambassador so he can be closer to his fiancé, Ni'Var president T'Rina—transport down to Lyrek and disable an automated defense system using an electromagnetic pulse. Book contacts Moll and L'ak posing as a fellow courier and learns that Moll is Malinne, the daughter of his mentor and namesake Cleveland Booker IV.

Summary from Wikipedia, CC BY-SA 4.0.