Burnham and Adira visit the Trill homeworld in hopes of unlocking the secrets trapped within Adira's mind. Back on the U.S.S. Discovery, Saru's efforts to help the crew reconnect with one another take a surprising turn.

Sonequa Martin-Green (Commander Michael Burnham)
Doug Jones (Captain Saru)
Anthony Rapp (Lt. Cmdr. Paul Stamets)
Mary Wiseman (Ensign Sylvia Tilly)
Wilson Cruz (Dr. Hugh Culber)
Rachael Ancheril (Commander Nhan)

Michelle Yeoh (Philippa Georgiou)

Ian Alexander (Gray Tal)
Andreas Apergis (Guardian Xi)
Blu del Barrio (Adira Tal)
Karen Robinson (Leader Pav)
Andrew Shaver (Commissioner Vos)
Annabelle Wallis (Zora)
Kenneth Welsh (Senna Tal)

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)
Julianne Grossman (Discovery Computer)
Raven Dauda (Dr. Tracy Pollard)
Elana Dunkelman (Disco Engineer #1)
Christine Nguyen (Disco Engineer #2)
David Benjamin Tomlinson (Lt. Linus)

• Trill Commissioner Vos says the population was decimated because of The Burn. At this time, the Trill homeworld is no longer part of the Federation and their society is on the brink of collapse. There are not enough suitable Trill for the symbionts.
  
• Adira's boyfriend Gray was Trill and was joined with the Tal symbiont. Soon after the joining, a fatal accident on their ship took Gray's life, and the symbiont had to be joined with another host. Adira volunteered.
  
• The previous Tal hosts were Kasha, Jovar, Madela, Cara, Senna, and Gray.
  
• After connecting with her symbiont, Adira provides Burnham with the location of Federation Headquarters.
  
• The Discovery computer appears to be merging with the sphere data. The computer's personality goes through a shift, even changing its voice. (Annabelle Wallis played the voice of the A.I. "Zora" in the Short Trek episode "Calypso".)
  
• The Trill homeworld and the Caves of Mak'ala were first seen in the DS9 episode "Equilibrium".
  
• DOT drones are once again shown to be repairing the Discovery's hull.