Burnham heads to the I.S.S. Charon with a special "gift" for the Emporer. With the help of an unexpected source, Stamets gains clarity while trapped inside the mycelial network. Saru asks for L'Rell's help with Tyler.

Sonequa Martin-Green (Specialist Michael Burnham)
Doug Jones (Commander Saru)
Shazad Latif (Lt. Ash Tyler)
Anthony Rapp (Lt. Paul Stamets)
Mary Wiseman (Cadet Sylvia Tilly)
Jason Isaacs (Captain Gabriel Lorca)

Michelle Yeoh (Captain Philippa Georgiou)

Mary Chieffo (L'Rell)
Wilson Cruz (Dr. Hugh Culber)

Sam Asante (Senior Guard)
Jeremy Crittenden (Lord Eling)
Raven Dauda (Dr. Tracy Pollard)
Billy MacLellan (Barlow)
Dwain Murphy (Captain Maddox)
Tasia Valenza (Shenzhou Computer)
Marie Ward (Junior Guard)

• Stamets and his mirror universe counterpart are trapped in the mycelial network. His mind puts them on a facsimile of the Discovery, though the plaque in engineering reads U.S.S. Stamets. He sees a vision of Hugh, who tells him that the mirror Stamets is the one who corrupted the mycelial network.
  
• L'Rell is able to eliminate the Voq personality, leaving only "Tyler" behind.
  
• In the mirror universe, Burnham was adopted by Georgiou, not Sarek.
  
• Burnham discovers Gabriel Lorca is actually from the mirror universe.
  
• Georgiou mentions the single biological difference between humans and Terrans is a photosensitivity to light.
  
• This episode introduces Raven Dauda as Dr. Tracy Pollard, a staff physician on Discovery.