The U.S.S. Discovery crew is intrigued by new addition Lieutenant Ash Tyler; Sarek seeks Michael Burnham's help, rekindling memories from her past; and Admiral Cornwell questions Captain Lorca's tactics.

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)

Jayne Brook (Admiral Katrina Cornwell)
Wilson Cruz (Dr. Hugh Culber)
James Frain (Ambassador Sarek)
Mia Kirshner (Amanda Grayson)
Kenneth Mitchell (General Kol)

Conrad Coates (Admiral Terral)
Emily Coutts (Lt. Keyla Detmer)
Julianne Grossman (Discovery Computer)
Luke Humphrey (Adjunct V'Latak)
Clare McConnell (Dennas)
Sara Mitich (Lt. Cmdr. Airiam)
Oyin Oladejo (Lt. Joann Owosekun)
Damon Runyan (Ujilli)
Jonathan Whittaker (Vulcan Director)

• Sarek's shameful memory was that he chose Spock over Michael when the Director of the Vulcan Expeditionary Service would only allow one of his "non-Vulcan experiments" in. He then arranged for a post in Starfleet. Instead of telling Burnham the truth, he let her think she wasn't good enough, that she was a disappointment. (Of course, Spock later refused the post and instead chose to join Starfleet. This caused friction between the two Vulcans.)
  
• Vulcan logic extremists bombed the learning center in an attempt to kill Burnham after Sarek and Amanda took her in after her parents died. He shared part of his katra to save her life.
  
• We learn Admiral Katrina Cornwell is a doctor and therapist. She previously had some sort of relationship with Lorca (and he calls her Kat). After spending the night with him, she realizes he's become unhinged and needs to step down.
  
• When Sarek is in recovery, Lorca conveniently suggests Cornwell take his place during the peace talks. The peace talk is a trap set by Klingon General Kol, and Cornwell is taken prisoner.
  
• Lorca appoints Tyler Discovery chief of security. He offers Burnham the bridge science officer position.
  
• Burnham helps Tilly set career goals, including getting a post on a Constitution-class starship, such as the Enterprise.