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 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.

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.

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

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.

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.

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.

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.

Upon returning from covertly observing a pre-warp culture, Lieutenant Reed realizes he lost his communicator somewhere on the planet. Archer and Reed return to recover the lost technology, only to find the natives found it first. Captured and interrogated, the crewmen find themselves doing even more damage to the culture, who have scanned the prisoners and know them to be of another race. Meanwhile, Tucker and Mayweather try to figure out how to activate the cloak on the Suliban cell ship so they can mount a discreet rescue.

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.

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

After Enterprise lends aid to a group of accused rebels, Captain Archer faces a tribunal and charges of conspiring against the Klingon Empire.

Mayweather temporarily leaves Enterprise to visit the cargo ship Horizon, where he was born and raised. Meanwhile, the Enterprise crew observes an unusual planetary event.

At Dr. Phlox's request, Enterprise attempts to retrieve 3 Denobulan scientists from the planet Xantoras, where the Goverment has ordered all off-worlders to evacuate within 3 days. Tucker, Reed, and Mayweather navigate a series of labyrinthine underground caves in search of the scientists. Meanwhile, Enterprise lends assistance to a damaged ship fleeing the planet. Doctor Phlox faces an ethical dilemma when one of the refugees of the ship refuses life-saving treatment. The patient, an Antaran, holds a grudge against Phlox stemming from a war between their races that ended 300 years ago and would rather die than be treated by a Denobulan. Phlox defies Archer's direct order to force treatment because it goes against the Deobulan code to yield to "the will of the patient."

Enterprise has been in the Delphic Expanse for six weeks and have yet to get any intel about the Xindi. Strange anomalies affect the ship, sending cargo flying violently through the bays, pockets of atmosphere losing gravity and other incidents defying the known laws of physics. T'Pol helps Trip's insomnia with an intimate Vulcan therapy. Archer and Trip find another race of Xindi imprisoned in a mine.

Hoshi Sato is contacted by a 400-year-old telepathic alien exiled on planet in the Expanse, shunned by his society because of his abilities. The alien offers to use his powers to help Enterprise find the Xindi and the weapon they are building, but only if Hoshi will stay with him while he works. She agrees to stay behind, while Enterprise confirms the Expanse has a second Sphere and is on its way to investigate.

His memory crippled, Archer awakens years in the future, after the Xindi have reduced Earth to a cinder and the remnants of humanity have settled on a distant planet. Now, Archer learns that he may be the key to undoing this tragedy.

Enterprise has found the location of the testing site of the Xindi weapon and gets some rather unexpected help.

With Reed and Hayes fighting over a training program and Trip seemingly making T'Pol jealous, Enterprise discovers a dying alien in a pod with technology similar to the Spheres.

Archer decides he should pilot a kamikaze shuttle to destroy the Xindi weapon. Temporal agent Daniels urges him to reconsider.

Following the destruction of the Xindi weapon, the Enterprise crew discovers that they have been sent back in time to 1944. However, history has been altered, leaving Nazi Germany in control of a large portion of the eastern United States.

After Silik attacks Trip, Vosk wants to make a deal with Archer: supplies of the ship for the completion of his time machine in return for a trip to the 22nd Century.

Noncorporeal aliens inhabit the bodies of Enterprise crew members to study how the crew reacts to a lethal virus infection that has afflicted Trip and Hoshi.

Captain Archer must convince Vulcans, Tellarites and Andorians to unite to find the Romulan ship.

Enterprise finds out the marauder was piloted telepathically by an Aenar, a subspecies from Andoria.

The men of Enterprise fall under the seductive control of three Orion women. Trip is the only male member of the crew not to succumb to the women.

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.

While attending a conference on a proposed interplanetary alliance, Trip and T'Pol find out from a dying woman that they have a baby. Investigation shows the woman was a member of the xenophobic organization Terra Prime.

Paxton threatens to destroy Starfleet Headquarters if all aliens don't leave Earth. Enterprise must shut down the verteron array on Mars, but it is extremely well defended.

In 2370, Commander William T. Riker is trying to clear his mind and relives the last mission of the first Enterprise on the holodeck.