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 Trill, Captain Burnham, Book, and Culber must pass a dangerous test to prove themselves worthy of the next clue. Adira reconnects with Gray and Saru’s first day as ambassador is complicated by his engagement to T'Rina.

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.

While undercover in a pre-warp society, Captain Burnham is forced to consider breaking the Prime Directive when a local tradition threatens Tilly's life. Meanwhile, Culber tries to connect with Stamets, and Adira steps up when Rayner assigns them a position on the bridge.

With Moll and L'ak finally in custody, the Federation is pulled into a diplomatic and ethical firestorm when the Breen arrive and demand they be handed over. Meanwhile, a frustrated Book looks for ways to help as Tilly, Adira, and Reno work to decipher the latest clue.

When Captain Burnham is trapped within a “mindscape” designed to test her worthiness to retrieve the Progenitor's powerful technology, Book, Rayner, and the crew of the U.S.S. Discovery must hold off the Breen long enough for her to escape.

After Moll and the Breen capture a mysterious structure that contains the Progenitors' power, Captain Burnham must lead a covert mission to retrieve it before the Breen figure out how to use it.

Trapped inside a mysterious alien portal that defies familiar rules of time, space, and gravity, Captain Burnham must fight Moll – and the environment itself – in order to locate the Progenitors' technology and secure it for the Federation. Meanwhile, Book puts himself in harm's way to help Burnham survive and Rayner leads the U.S.S. Discovery in an epic winner-takes-all battle against Breen forces.