After using the Defiant to repel a Tholian attack, the power-hungry Archer and Enterprise crew set about using this advanced ship to seize control of all of Earth's Terran Empire. As Archer takes full command of the Defiant and reviews the alternate history of Starfleet, his duplicitous lover Hoshi, a traitorous T'Pol and a reptilian Gorn stowaway hatch schemes of their own.

Scott Bakula (Commander Jonathan Archer)
Jolene Blalock (Sub-Commander T'Pol)
John Billingsley (Doctor Phlox)
Linda Park (Ensign Hoshi Sato)
Anthony Montgomery (Sargeant Travis Mayweather)
Dominic Keating (Major Malcolm Reed)
Connor Trinneer (Commander Charles 'Trip' Tucker III)

Gary Graham (Ensign Soval)
Gregory Itzin (Admiral Black)
Derek Magyar (Ensign Kelby)
John Mahon (Admiral Gardner)
Pat Healy (Alien)

Majel Barrett (Defiant Computer Voice)
David Sobolov (Slar)

• The crew that arrived on the Defiant in Part 1 wear the TOS uniforms in this episode (since they arrived in EV suits).
  
• The Defiant finds rebel Andorian, Vulcan, and Tellarite ships attacking the I.S.S. Avenger, an NX-class starship commanded by Admiral Black. Soval (sporting a goatee) was the science officer on the Avenger. Archer destroyed the rebels, allowing one to escape as a warning.
  
• Ensign Kelby was killed by the Gorn. Reed put on the TOS red shirt uniform and was also critically injured by the Gorn; he was out of commission for the rest of the episode.
  
• T'Pol notes that "It may take centuries, but humanity will pay for its arrogance." See the DS9 episode "Crossover".
  
• After the destruction of the Avenger, Hoshi poisons Archer, takes over the Defiant (with Mayweather's help) and declares herself Empress Sato, ordering Fleet Admiral Gardner to surrender.
  
• This is the only on-screen appearance of Admiral Gardner (albeit his mirror universe counterpart).
  
• David Sobolov provides the voice of the Gorn, Slar, but the character was fully a computer generated creation. (Stunt coordinator Vince Deadrick Jr. performed the motion capture.)