With Archer trapped in the 31st century, the Suliban holds the crew hostage. Meanwhile, Daniels worries that his actions may affect history.
Disputing the long-accepted history that the current encounter between Vulcans and humans is the first ever, T'Pol tells Trip and Archer about a small group of Vulcans, which included her great-grandmother, crash-landing in Pennsylvania in the mid-1900s.
When Archer receives orders to leave Romulan airspace, he must choose whether or not to abandon Reed, who is pinned to the hull.
Stopping for repairs, the ship docks at a mysterious space station.
When his dog picks up a deadly alien virus, Archer spends a troubling night with him in the ship's sick bay.
With their ship low on fuel, the Enterprise crew finds themselves stranded on a mining colony controlled by Klingons.
Archer and T'Pol pursue a fugitive who has been on the run from Vulcan authorities for almost two decades.
Reed and Archer revisit a planet in order to retrieve a communicator only to be captured and set for execution.
The crew's behavior becomes erratic as the result of a black hole.
Hoshi experiences strange events after using the transporter for the first time and is convinced she has been altered during the trip.
Trip frees an exotic alien female prisoner and helps her escape her captors.
The crew finds shelter in a maintenance shaft during a deadly radioactive storm.
Trip is caught in a game of cat-and-mouse with an alien while they are both stranded on a deserted moon. As the scorching sun rises, it threatens to burn both of them alive.
Dr. Phlox experiences resistance from Vulcan doctors during a medical conference as he searches for information about a terminal disease which has infected T'Pol.
Captain Archer must mediate a dispute over a small planet looming between the Vulcans and Andorians.
After Captain Archer investigates a small ship found floating in space, the Sulibans and Tholians attack the Enterprise, laying claim to the newly-discovered ship.
When Archer and Trip are accused of smuggling and arrested, they are held aboard a prison ship en route to a penal colony.
The Enterprise is overtaken by an alien craft, during which time noncorporeal creatures inhabit the bodies of crew members in order to snatch their souls.
Archer is tried in a Klingon tribunal and faces a penalty of death for helping refugees escape the empire.
Mayweather visits his old cargo ship home following his father's death, only to learn that things have drastically changed. Meanwhile, Enterprise explores an unusual planetary phenomenon close to Earth.
The Enterprise crew rushes to evacuate a team of geologists during a planetary invasion. Meanwhile, Phlox has to save the life of a member of an alien race that is hostile to his race.
When the Enterprise crew makes contact with a three-gendered species, Trip tries to help a member of the third gender, known as Cogenitors, upon learning of their poor treatment.
When a ship containing two frozen cybernetic Borg drones is found in Earth's Arctic Circle, Archer and the Enterprise crew are brought in to investigate. After thawing out, the alien beings prove to be more of a threat than initially realized.
Archer recounts for T'Pol the story of when, as pilots, he and a rival were in competition to be the first to break the Warp 2 barrier.
A bounty hunter captures Archer and plans to give him over to the Klingons for a reward. Meanwhile, T'Pol is infected with a virus that unleashes the Pon Farr, a recurring mating urge within Vulcans.
After an alien race known as the Xindi strike a devastating blow against Earth, the Enterprise is given a new directive, and Archer and the crew must now set out for the far end of the galaxy to battle the Xindi and stop them from completely annihilating Earth. Along the way, they continue to be trailed by the Klingons, hellbent on destroying Captain Archer.