Commander Una Chin-Riley faces court-martial along with possible imprisonment and dishonorable dismissal from Starfleet, and her defense is in the hands of a lawyer who’s also a childhood friend with whom she had a terrible falling out.

Anson Mount (Captain Christopher Pike)
Ethan Peck (Lieutenant Spock)
Jess Bush (Nurse Christine Chapel)
Christina Chong (Lt. La'an Noonien-Singh)
Celia Rose Gooding (Ensign Nyota Uhura)
Melissa Navia (Lt. Erica Ortegas)
Babs Olusanmokun (Dr. Joseph M'Benga)
Rebecca Romijn (Lt. Commander Una Chin-Riley)

Yetide Badaki (Neera Ketoul)
Adrian Holmes (Admiral Robert April)
Melanie Scrofano (Captain Batel)

Jim Annan (Una's Father)
Anna Claire Beitel (Young Una)
Catherine Black (Una's Mother)
Eugene Clark (Vulcan Judge)
Nicky Guadagni (Admiral Javas)
Beth Hornby (Guard)
Alex Kapp (U.S.S. Enterprise Computer)
Graeme Somerville (Vice Admiral Pasalk)
Iain Stewart (Jag Defender)
David Benjamin Tomlinson (Tellarite Judge)
Kimberly-Ann Truong (Illyrian Assistant)

• Number One translates the episode's title as "to the stars through hardship". Ad Astra per Aspera was Starfleet's motto before the Federation.
  
• Under Starfleet Code 8514, Una is granted asylum and she is found not guilty.