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

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.

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.

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.

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.

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

After Hoshi uses the transporter to avoid running into a storm, she starts to feel very strange.

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

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

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.

Enterprise encounters a hyper-giant star. While there, they make first contact with the Vissians, a technologically sophisticated race with three genders. While making quick friends, and eagerly learning about the advanced technology, Trip gets curious about the Vissians third gender, known as the Cogenitor, who is crucial in the Vissian reproductive process. Against the wishes of the Vissians, Trip befriends the Cogenitor and encourages it to defy its cultural boundaries, which the Vissians are made aware of, and are angered by.

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.

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

After an attack by Osaarian pirates, Enterprise follows them to a mysterious sphere.

Archer, Reed and Sato are transformed into aliens while visiting a planet.

Enterprise helps an alien woman, Rajiin, seeking to escape her life as a sex slave. Once on board she uses her alien abilities to gather biometric data about humans and is recaptured by her employers, the Xindi council.

Enterprise answers a distress signal from a stranded Vulcan ship, only when arriving they find the ship completely desolate, wrecked - and filled with Vulcan zombies.

Archer decides to make a fast-growing clone of Trip to help save his life while Enterprise is stranded in a dangerous field with nucleonic particles.

Enterprise is taken over by religious zealots who want to use the ship in a war against heretics.

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

Archer and the Xindi Degra are in a shuttle. With Degra suffering from memory loss, Archer tells him they escaped together from a prison and that the Insectoids took power after destroying Earth.

Captain Archer orders the crew of Enterprise to save a Xindi-Insectoid hatchery.

Captain Archer has been returned to Enterprise by the Xindi council awaiting a hearing. But after a heavy attack by the Reptilians, Enterprise is stranded without a functional warp drive. They meet another ship in trouble because of space anomalies. The ship's captain isn't willing to trade in their warp coil and Archer must make a tough decision. Meanwhile T'Pol is having some strange sensations and can't control her emotions.

As the crew continues to repair the ship and mourn the dead, Archer works to create trust and form a partnership with members of the Xindi council.

Enterprise has arrived at the location of the Xindi Council and with the help of Degra, Archer can make his plea in front of the five races of Xindi. Archer needs to prove that the Sphere Builders have been telling lies. While the Primates and Arboreals are already aware of the truth, convincing the other three races will not be easy. The Reptilians and Insectoids refuse to even listen to Archer. Meanwhile, the Sphere Builders haven't been sitting still, and have arranged a secret meeting with the Reptilians.

While the Reptilians force Hoshi to decipher a launch code, the Primates, Arboreals and Archer think of a way to stop the Xindi weapon.

Archer takes Degra's ship to try to prevent Earth from being destroyed and gets some unexpected help. Enterprise tries to destroy Sphere 41, but the Sphere Builders know about the plan.

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 Klingon ship is attacked, it's discovered the imprisoned Dr. Soong's genetically enhanced humans are responsible. Archer takes him to prevent a war.

While Enterprise travels to Andoria to warn them of the attack, Archer tries to bring the Kir'Shara to the High Command.

Dr. Emory Erickson comes aboard to supposedly conduct tests for subquantum transportation. However, he seems to have a different agenda.

Enterprise escorts Tellarites to peace talks with Andorians. While transporting they rescue Andorians and say the Tellarites attacked them. Enterprise is soon attacked by an Andorian ship, and Archer must prove who is responsible.

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.

While Enterprise is visiting Earth, Phlox is abducted by the Klingons and forced to research a cure for a virus destined to wipe out the race. Reed is tapped by a secret agency and ordered to betray Archer. Trip transfers to the Columbia.

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.

The Mirror Universe saga concludes as Archer declares himself captain of a formidable starship from the future, while his alien crew launch a rebellion in a desperate bid to keep him from achieving ultimate power.

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.