In the mid-22nd century, the Earth ship Enterprise is launched under the command of Captain Jonathan Archer. When the crew rescues an alien from a crashed spaceship, Earth gets its first look at the alien's race - the Klingons. Archer and his crew must walk a fine line as they attempt to communicate with the Klingon pilot, whose language is completely unknown, and whose homeworld wants him back. Is this the beginning of friendship...or interstellar war?

Enterprise is sent to help the freighter Fortunate after an attack. However, its first officer, Ryan, is hiding something.

Enterprise tries to rescue a Klingon ship from sinking into a gas giant.

T'Pol is being recalled because of Enterprise's involvement in the destruction of the P'Jem sanctuary. She and Captain Archer are later kidnapped while visiting the planet Coridan.

When Enterprise encounters a ship of Vulcan pilgrims, T'Pol is convinced by one of them to perform a Vulcan mind meld.

A fibrous, web-like alien creature comes aboard the ship and several of the crew becomes entangled in it including Archer and Trip, and it seems Hoshi is the only one who can try to communicate with the creature.

Enterprise is planning a trip to the relaxation planet Risa, when it gets an urgent request from the Vulcan High Command. They must pick up ambassador V'Lar who has fallen in disgrace. Apparently she misused her position during negotiations on the planet Mazar and has been evicted. After Enterprise picked up V'Lar and is on its way for a meeting with the Vulcan warship Sh'Ran, suddenly a Mazarite ship appears. They want V'Lar for further interrogating. When captain Archer wants to discuss it first with Starfleet Command, they open fire.

Enterprise discovers a mining colony of the Paraagans. The crew gets an invitation for a meeting on the surface and a shuttle pod tries to break through the atmosphere. All of a sudden just under the shuttle a giant explosion begins and scorches the earth beneath. All 3600 colonists are reported dead. After examination, Enterprise finds out plasma leaking from the pod's vents ignited tetrazine in the atmosphere. Lieutenant Reed, however, ensures he closed the plasma vents before the shuttle went of. After conversations with admiral Forrest of Starfleet Command, Captain Archer learns that Enterprise's mission is canceled and they must return home, not to return to space for another ten or twenty years. When the ship has altered course, crewman Daniels, a time traveler, pays a visit to captain Archer.

Captain Archer and temporal agent Daniels have been stranded in the 31st century. In a library they investigate the damage to the time line and try to find way a to get Archer back in his own century. Meanwhile Silik the Suliban leader is trying his utmost to find the whereabouts of Archer and he is willing to go far for the answer. But the crew of Enterprise has plans of their own. Trip finds a way to use the com system and is able to speak with Reed. Together they try to contact other crew members and make plans to purge Enterprise of the Sulibans.

After previously offending the Kreetassans, Enterprise attempts to make a better second impression, only to upset the alien race once again. A frustrated Captain Archer returns from the planet only to be further upset to find that his dog Porthos, has been affected by a pathogen native to the world. While Phlox works around the clock treating Porthos, Archer stands vigil in sickbay, experiencing first-hand the quirky everyday life of his Denobulan Doctor.

Captain Archer is asked to negotiate between the Andorians and Vulcans who are fighting over a small planet.

Enterprise discovers a pod with the body of a human that seems to be wanted by both Sulibans and Tholians.

An Arctic research team makes a startling find: cybernetic creatures - Borg - buried in the ice. When the revived aliens seize control of a spacecraft, it's up to Archer to keep them from contacting the Collective and threatening Earth.

After his close friend and colleague A.G. Robinson is killed in a mountain climbing accident, Captain Archer tells T'Pol about the Warp 2 test flight almost ten years earlier.

An alien probe launches a devastating attack on Earth. Archer, still being hunted by the Klingons, brings the Enterprise back home to investigate.

The crew take some time off. Archer meets an old friend, Captain Erika Hernandez. T'Pol takes Trip to Vulcan, with a surprise waiting. Phlox finds out Earth has become xenophobic.

After a bombing destroyed the Earth embassy on Vulcan, a group known as the Syrrannites are suspected. T'Pol receives a map from her Syrrannite mother, leading into a dangerous desert, the Forge.

Set in the dark and oppressive Mirror Universe, Commander Archer leads a mutiny in a bold attempt to seize control of an advanced starship - a vessel from the future that may be the key to saving the Terran Empire.