ENT Season 3 Episode 21 E2

Plot

To reach the rendezvous with Degra in three days, Enterprise approaches a nebula that contains a subspace corridor defended by Kovaalan vessels. The corridor lets them traverse the distance in minutes. Suddenly, an older yet enhanced copy of Enterprise appears, captained by a half-Vulcan man named Lorian, who explains that after the Enterprise enters the corridor, it will destabilize, causing Captain Archer's version to travel 117 years into the past. Confronted with this situation, and not wanting to contaminate Earth's time stream, it then turns itself into a generational ship to await the Xindi crisis. Arriving on board, Lorian reveals that he is the son of Commander Tucker and Sub-Commander T'Pol. Archer also meets his great-granddaughter, Karyn Archer, who is part Ikaaran, as Enterprise will rescue her great-grandmother Esilia from a spatial-anomaly field.
Lorian, after considering his knowledge of events, believes that the wormhole must be avoided altogether. Archer and Lorian then disagree over whether to implement an engine modification to Enterprise, since there is a 22% chance that it might destroy the ship. Archer then meets old T'Pol on board old Enterprise, and considers a plan where his ship could pass through safely, due to alternative modifications she suggests. A frustrated Lorian then reveals a secret plan: to steal the newer plasma injectors from Enterprise so they can confront the Xindi in place of their ancestors.
Lorian leads a raid and successfully steals the parts, but the old Enterprise is disabled by Archer as it is about to go to warp and Lorian is put in the brig. Archer is angry at having his own method of stealing engine components (as seen in Damage) used against him. Lorian reveals that he had a chance to stop the Xindi Probe from The Expanse from attacking Earth, but failed because he hesitated, then the two captains finally agree to work towards their shared mission. Meanwhile, T'Pol meets her older self and discuss her addiction to Trelium-D and her relationship with Tucker. The older T'Pol confirms the younger's deepest fears: in Tucker, there is something bringing irrationality into her life which she can not ever control, but which will nurture her and have a positive irreplaceable effect on her life and spirit. The Enterprises then enter the nebula, but Archer's is quickly disabled. Lorian's then tows it into the corridor using a tractor beam, intending, as it turns to attack the Kovaalan ships, to follow shortly. Archer's Enterprise arrives safely, but old Enterprise never emerges and Archer wonders if, by successfully traversing the corridor, they ceased to exist. His thoughts are cut short when Degra arrives for their rendezvous.