Burnham and Stamets navigate a dangerous alien landscape in a race against time to save Tilly’s life, but Stamets is not at all prepared for what they find in the process. Section 31 is assigned to help track down Spock, much to Pike’s dismay.

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 (Hugh Culber)
Anson Mount (Captain Christopher Pike)

Michelle Yeoh (Philippa Georgiou)

Jayne Brook (Admiral Katrina Cornwell)
Alan van Sprang (Captain Leland)
Rachael Ancheril (Commander Nhan)
Bahia Watson (May Ahearn)

Hannah Cheesman (Lt. Cmdr. Airiam)
Emily Coutts (Lt. Keyla Detmer)
Patrick Kwok-Choon (Lt. Gen Rhys)
Oyin Oladejo (Lt. Joann Owosekun)
Ronnie Rowe Jr. (Lt. Ronald Bryce)
Julianne Grossman (Discovery Computer)

• May takes Tilly into the mycelial network to help her kill the "monster" that is destroying the network and killing the JahSepp.
  
• Burnham finds out Georgiou is now a Section 31 agent, working under Captain Leland.
  
• Agent Ash Tyler is assigned to Discovery as the Section 31 liaison during the search for Spock.
  
• Hugh Culber is discovered trapped inside the mycelial network. May helps the crew bring him out using the cocoon.