When the U.S.S. Discovery's crucial mission does not go according to plan, Burnham realizes what must ultimately be done. The crew prepares for the battle of a lifetime as Leland's Control ships get closer.

Sonequa Martin-Green (Commander Michael Burnham)
Doug Jones (Commander Saru)
Anthony Rapp (Lt. Cmdr. Paul Stamets)
Mary Wiseman (Ensign Sylvia Tilly)
Shazad Latif (Agent Ash Tyler)
Wilson Cruz (Dr. Hugh Culber)
Anson Mount (Captain Christopher Pike)

Michelle Yeoh (Philippa Georgiou)

Jayne Brook (Admiral Katrina Cornwell)
Mary Chieffo (Chancellor L'Rell)
Yadira Guevara-Prip (Me Hani Ika Hali Ka Po)
Mia Kirshner (Amanda Grayson)
Tig Notaro (Commander Jett Reno)
Ethan Peck (Lieutenant Spock)
Rebecca Romijn (Number One)
Alan van Sprang (Captain Leland)
Rachael Ancheril (Cmdr. Nhan)

Emily Coutts (Lt. Keyla Detmer)
Patrick Kwok-Choon (Lt. Gen Rhys)
Oyin Oladejo (Lt. Joann Owosekun)
Ronnie Rowe Jr. (Lt. Ronald Bryce)
Sara Mitich (Lt. Nilsson)
Raven Dauda (Dr. Tracy Pollard)
Julianne Grossman (Discovery Computer)
Zarrin Darnell-Martin (Nurse)
Glenn Hetrick (K'vort)
Thom Marriott (Council Member)
Hannah Spear (Siranna)
Samora Smallwood (Lt. Amin)
Hanneke Talbot (Lt. Mann)
Kyana Teresa (Doctor)
Chai Valladares (Lt. Nicola)
Nicole Dickinson (Yeoman Colt)

• Part 1 of the Season Finale.
  
• The crew abandons ship to the U.S.S. Enterprise and sets Discovery's auto-destruct. When the countdown reaches 0, the Sphere archive's firewall disables it.
  
• The next signal takes Discovery to the planet Xahea, and Tilly reveals she knows the Queen of Xahea, Po. (Po was introduced in the Short Trek episode "Runaway".) Po's engineering and dilithium expertise is needed to harness the crystal's power.
  
• The crew fabricates a new time suit, which Burnham will take into the future, with Discovery in tow.