Captain Burnham and the U.S.S. Discovery are sent to retrieve a mysterious 800-year-old Romulan vessel; until the artifact hidden inside is stolen, leading to an epic chase. Meanwhile, Saru is offered the position of a lifetime, and Tilly's efforts to help pull her into a tangled web of secrecy.

On Saru's last mission as Captain Burnham's Number One, the team ventures to a seemingly abandoned planet to hunt for what might be the greatest treasure in the galaxy.

On the way to the next clue, the U.S.S. Discovery is sabotaged by a mysterious weapon, leaving Captain Burnham, Rayner, and Stamets as the only crew members who can possibly save the ship in time.

Captain Burnham and Book journey into extradimensional space in search of the next clue to the location of the Progenitors' power. Meanwhile, Rayner navigates his first mission in command of the U.S.S. Discovery, and Culber opens up to Tilly.