After answering a distress signal from the U.S.S. Enterprise, the U.S.S. Discovery welcomes aboard Captain Christopher Pike and beings a new mission to investigate the meaning behind seven mysterious red signals. Michael Burnham grapples with her past growing up on Vulcan with her foster parents and brother Spock.

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

James Frain (Ambassador Sarek)
Mia Kirshner (Amanda Grayson)
Tig Notaro (Commander Jett Reno)

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)
Ethan Peck (Lt. Spock)
Sean Connolly Affleck (Lt. Evan Connolly)
Rachael Ancheril (Commander Nhan)
Arista Arhin (Young Michael Burnham)
Raven Dauda (Dr. Tracy Pollard)
Julianne Grossman (Discovery Computer)
Liam Hughes (Young Spock)
Sara Mitich (Lt. Nilsson)
David Benjamin Tomlinson (Lt. Linus)

• Pike has been sent by Starfleet to investigate the red bursts. When the Enterprise suffers from a systems failure, he takes command of the U.S.S. Discovery. He is joined by security officer Cmdr. Nhan and science officer Lt. Connolly.
  
• Wilson Cruz (Dr. Hugh Culber) was promoted to regular cast member, and he now appears in the opening credits.
  
• This is the first appearance of Jett Reno, former chief engineer aboard the U.S.S. Hiawatha NCC-815, a medical frigate that went missing during the Federation/Klingon war and was presumed destroyed.
  
• While injured on the Hiawatha, Burnham has a vision of a red angel.
  
• This is the first appearance of Anson Mount as Captain Christopher Pike.
  
• Due to issues with the makeup, Hannah Cheesman now plays Lt. Cmdr. Airiam. The former actress, Sara Mitich, now plays human Lt. Nilsson.
  
• This is the first appearance of the Saurian science officer, Lieutenant Linus.
  
• Ethan Peck makes his debut as the voice of Lt. Spock.
  
• This episode opens with Burnham recalling the story of "The Girl Who Made the Stars", which will later become an animated Short Trek.