Mariner faces her past in the season four finale.

Tawny Newsome (Lt. Beckett Mariner)
Jack Quaid (Lt. Brad Boimler)
Noël Wells (Lt. D'Vana Tendi)
Eugene Cordero (Lt. Sam Rutherford)
Dawnn Lewis (Captain Carol Freeman)
Jerry O'Connell (Commander Jack Ransom)
Fred Tatasciore (Lieutenant Shaxs)
Gillian Vigman (Dr. T'Ana)

Shannon Fill (Cadet Sito Jaxa)
Robert Duncan McNeill (Nick Locarno)
Wil Wheaton (Cadet Wesley Crusher)

Eric Bauza
Phil LaMarr (Admiral Alonzo Freeman)
Jessica McKenna (Ensign Barnes)
Nolan North
Gabrielle Ruiz (Lieutenant T'Lyn)
Paul Scheer (Lt. Cmdr. Andy Billups)
Carl Tart (Lieutenant Kayshon)
Paul F. Tompkins (Dr. Migleemo)
Kari Wahlgren
Ariel Winter (D'Erika Tendi)

• The episode begins with a flashback to Starfleet Academy 13 years ago (2368), showing Mariner (a cadet 3rd class) and Nova Squadron members Locarno, Sito, Wesley Crusher and Josh Albert, before the events of the TNG episode "The First Duty". (In the TNG episode, Joshua Albert isn't actually shown since he had died; the fifth Nova Squadron member, Cadet Hajar, is not seen in the flashback.)
  
• Shannon Fill (Cadet Sito Jaxa) and Wil Wheaton (Cadet Wesley Crusher) return to voice their respective characters in the flashback.
  
• Locarno has an off-market Ferengi-knockoff Genesis Device.
  
• The final battle is remeniscent of Star Trek II: The Wrath of Khan, and ends with the detonation of the Genesis Device, killing Locarno in the process. Starfleet names the resulting M-class planet Locarno since it includes his genetic material.
  
• Rutherford notes that Locarno looks just like Tom Paris, but Boimler doesn't see it.