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 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.

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.

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.

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 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.

The safety of Enterprise rests on Reed's shoulders when the ship becomes trapped in a Romulan minefield and Romulan ships are closing in on them.

Enterprise seeks repairs from their encounters with the Romulans, where they stop at a desolate but idyllic repair station. But all is not what it seems when Mayweather is suddenly found dead.

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.

T'Pol asks Captain Archer to join her on a mission to capture a Vulcan fugitive that escaped her years ago.

T'Pol must save the ship after the crew becomes obsessed with trivialities during the approach to a black hole.

After receiving a warning about a radioactive storm approaching Enterprise, the crew is forced to take shelter in the ship's catwalk.

Trip's shuttlepod is shot down by a hostile race and is forced to land on a deserted moon. There he must team up with the alien who shot him down in order to find a way back to Enterprise.

Enterprise is held captive by non-corporeal beings who claim to be explorers.