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.

Sonequa Martin-Green (Captain Michael Burnham)
Anthony Rapp (Lt. Cmdr. Paul Stamets)
Mary Wiseman (Lieutenant Sylvia Tilly)
Wilson Cruz (Dr. Hugh Culber)
Blu del Barrio (Ensign Adira Tal)
Callum Keith Rennie (Commander Rayner)
Tig Notaro (Cmdr. Jett Reno)
David Ajala (Cleveland Booker)

Annabelle Wallis (Zora)
Hannah Cheesman (Lt. Cmdr. Airiam)
Eve Harlow (Moll)
Elias Toufexis (L'ak)

Emily Coutts (Lt. Cmdr. Keyla Detmer)
Patrick Kwok-Choon (Lt. Cmdr. Gen Rhys)
Oyin Oladejo (Lt. Cmdr. Joann Owosekun)
Ronnie Rowe Jr. (Lt. Cmdr. Ronald Bryce)
Orville Cummings (Lieutenant Christopher)
David Benjamin Tomlinson (Lieutenant Linus)
Joshua Bainbridge (Regulator)
James Cade (Weapons Dealer)
Minh Ly (Construction Worker)

• Moll planted a Krenim temporal bug on Adira while on Trill. It is causing the ship to jump between different points in time.
  
• One jump is 30 years in the future, where the Federation has been destroyed by the Breen using the progenitor technology, and the U.S.S. Discovery crew is dead (except for Zora).
  
• Bryce and Ariam make an appearance in the past, when Lorca was in command. (He does not appear in the episode, only mentioned in dialogue.)
  
• Doug Jones (Saru) does not appear in this episode, and is not credited in the title sequence. It is the first episode of Discovery that does not feature him.
  
• Ian Alexander (Gray Tal) appears via voice comm to Adira, but is not credited.