As Enterprise heads toward its rendezvous with Degra and a fateful meeting with the Xindi Council, the crew faces a dangerous trek. To reach their destination, they must enter a subspace corridor guarded by the Kovaalans, a species that isn't very tolerant of trespassers. Suddenly, the crew detects another ship, an NX-class Starfleet vessel — Enterprise NX-01. The ship's captain, Lorian, tells the captain that the current mission will not be successful. If Archer takes his ship into the subspace corridor, it will be thrown back in time 117 years.

David Andrews (Captain Lorian)
Randy Oglesby (Degra)
Tucker Smallwood (Xindi-Primate)
Rick Worthy (Xindi-Arboreal Janaar)
Tess Lina (Karyn Archer)

Tom Schanley (Greer)
Steve Truitt (Crewman #1)

• Lorian is T'Pol and Tucker's son. Karyn Archer is Archer's great granddaughter.
  
• When the other Enterprise appears, they wonder if it's the NX-02 Columbia.
  
• Archer also wonders if the other Enterprise is why the Xindi kept asking about the other Starfleet ships in the Expanse.
  
• The alternate Enterprise is presumed destroyed by the Kovaalans or ceased to exist when the real Enterprise made it through the corridor.
  
• This episode's premise is very similar to the Deep Space Nine episode "Children of Time".