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?

Captain Jonathan Archer, T'Pol and Trip meet Sarin and she explains that Klaang is a courier, bringing an important message from her to the leaders of the Klingons in Kronos about rebels Suliban that intend to promote the Temporal Cold War among the Klingons. Archer feels the need of rescuing Klaang and travels to the Suliban mother-ship with Trip to bring the Klingon back to Enterprise. T'Pol seems to understand that loyalty is an emotion that cannot be avoided by humans.

Captain Archer wants to convert curiosity into deeds and decides to enter a ship floating in space. Hoshi has trouble adjusting to life on Enterprise.

Archer sends an away team to a habitable, luscious planet for observation. But when a storm occurs, the team begins to experience paranoid delusions.

After helping to repair the warp drive on board of a Xyrillian ship, Trip notices a strange bulging on his arm.

Enterprise tries to find out what happened on Terra Nova, the first colonization attempt outside Earth's solar system.

Archer, Trip and T'Pol are captured by the Andorians at a Vulcan monastery on P'Jem. They believe that the monastery is being used to spy on Andoria.

Enterprise discovers a comet which contains the very rare element eisilium. Then unexpectedly a Vulcan ship arrives. Captain Vanik tells they're interested in human behavior.

T'Pol finds unusual neutrino readings on a planet with a preindustrial society.

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

Enterprise has a group of aliens watching a stellar phenomenon on board. When the ship is miraculously saved from blowing up, crewman Daniels has an important message for Archer.

After an attack by a mysterious ship, Archers orders Enterprise's return to Jupiter to install phase cannons; Hoshi makes plans for Malcolm's birthday.

Phlox is asked to save the Valakians from annihilation by disease. However, he discovers something unusual about the Menk, another humanoid race on the planet.

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.

While returning to Enterprise in Shuttlepod One, Trip and Reed see apparent evidence that the ship has been destroyed. With only days of oxygen left, they must find a way to survive long enough for rescue.

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

Lieutenant Reed discovers a rogue planet, which has broken out of orbit and therefore is devoid of any light. Life is still possible in some places because heat is bubbling up from under the surface, but T'Pol doesn't detect any humanoid life. Further scans however give a strange energy reading which seems to be coming from a ship on the surface. After the crew has landed, they encounter the Eska. The Eska come from another planet and they say they are hunting for the drayjin, an animal considered a delicacy. When captain Jonathan Archer tries to sleep on the planet, he hears a voice calling him by his name. A human female is wandering in the forest. Somehow he seems to know her.

Almost the entire crew is left unconscious when four Ferengi pirates raid Enterprise. A still conscious Trip is the only one who can get rid of them.

The crew of Enterprise searches for a seemingly abandoned ship on a desert planet.

Archer and Mayweather are captured by the Tandarans and placed in a Suliban internment camp.

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 is for the second time on its way to Risa when yet again another urgent matter comes up: a distress call. It comes from a small vessel. The owner, Zobral, is extremely happy with the help from Enterprise and invites Captain Archer to his home world for a good meal and a game of Geskana. When Archer and Trip have landed on the desert planet, Enterprise gets a message from the Torothan Chancellor Trelit. He says Zobral isn't as nice a man as captain Archer thinks.

The members of the Enterprise crew are faced with various misadventures and challenges while taking a two day break from their duties on the planet of Risa.

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.