List of Star Trek: Enterprise story arcs

Star Trek: Enterprise relied upon story arcs more often than previous Star Trek series, with the exception of Deep Space Nine (although DS9 relied more on one overriding story arc rather than multiple storylines as Enterprise did).

The first two seasons had only two story arcs which re-emerged sporadically, while the entire third season was a single arc that also included episodes from the second and fourth seasons. Beginning with the fourth season, the format of the series was altered so that the season featured a number of two- and three-episode arcs, which more than doubled the total number of arcs. A number of arcs overlap while some arcs set the scene for later arcs.

See also List of Star Trek: Enterprise episodes.

__NOTOC__ There are two kinds of story arcs detailed here:

• Plot story arcs
• Character story arcs

Plot story arcs

Temporal Cold War

An unidentified force from the 29th century is attempting to disrupt history through a Temporal Cold War (TCW). These episodes involve a time traveller from the 30th century, Daniels, who works with Archer and his crew to make sure history is not changed. The Xindi arc (see below), which also involves time travel, is sometimes seen as an offshoot of the TCW. Also included in this arc is a subplot involving the aftermath of Archer freeing a group of wrongly detained Suliban.

The Xindi

A mysterious space probe attacks Earth, [...] 7 million people. After receiving information from individuals involved in the Temporal Cold War as to the origin of the weapon, the Enterprise NX-01 is assigned to enter a dangerous region of space to track down those responsible and prevent further attacks on Earth. This arc spanned an entire season and also overlapped into both the second and fourth seasons. The fourth season in particular sees Archer and his crew dealing with the fallout from the Xindi mission, with references to the event occurring in more episodes than are listed below.

Andorians vs. Vulcans

These episodes chronicle the tensions existing between Vulcan and Andoria, two worlds that eventually put aside their differences and ally with Earth to form the United Federation of Planets. This arc intersects with the "Surak's Followers" arc, below.

Risa

A loosely knit arc from the end of the first season sees Enterprise heading for the pleasure planet, Risa, but encountering detours along the way.

Fugitive from the Klingons

This second season arc sees Captain Archer pursued by Klingon forces for alleged violations of Klingon law.

Augments

Genetically engineered humans created in the 20th century and nurtured by a brilliant but insane scientist hijack a Klingon vessel and attempt to rescue their adopted "father".

Surak's followers

Vulcan undergoes an upheaval as followers of Surak's principles try to overthrow the current government which is being secretly manipulated by the Romulans.

Romulan drone ships

The Romulans use the mental abilities of an Andorian race called The Aenar to control a series of prototype, remote-controlled vessels designed to spark a war between Earth, Vulcan, Andorians, and the Tellarites.

Klingon Augments

In this sequel to the human augments arc, the Klingons attempt to create their own genetically engineered race using Augment DNA from Dr. Soong's embryos. The result: a virus that is [...] millions of Klingons and changing their appearance. This story arc is used to present a historical reason within Star Trek cannon for the Klingons of the original Star Trek series' appearance. As seen in the Star Trek of the 60's, Klingons were basically humans with darker skin, noticeably absent head crests and somewhat less aggressive behavior.

Birth of the Federation ("BOTF")

These episodes follow the early steps leading toward the creation of the United Federation of Planets. The arc incorporates elements of the Vulcan vs. Andorians arc, the Surak's follower's arc, and the Xindi arc.

Mirror Universe

These two episodes take place completely within the Mirror Universe, and are accompanied by a unique version of the opening and closing credits. In this storyline, Commander Jonathan Archer of the Terran Empire stages a mutiny aboard the I.S.S. Enterprise in order to capture a starship that is not only from an alternate universe, but also from the future. This arc serves both as a prequel to the Star Trek: The Original Series episode "Mirror, Mirror", and as a sequel to the TOS episode "The Tholian Web".

Section 31

This arc contains the episodes featuring "The Section" which later will become known as Section 31 in Star Trek: Deep Space Nine. This arc overlaps the Klingon Augments arc.

Character story arcs

Trip and T'Pol

This arc, which was hinted at during the first two seasons, but finally blossomed in the third season, details the evolving relationship between Trip Tucker and T'Pol. Many Xindi arc episodes touched on the Trip/T'Pol arc, as did numerous fourth season storylines.

Key episodes:

T'Pol

T'Pol's own evolution as a Vulcan was the focus of an ongoing character arc that started in the very first episode. Beginning with her initial distrust of humans, this arc would see her come to bond with her human crewmates (particularly Archer and Tucker), experiment with mind-melding (initially causing her to contract an HIV-like condition as a result), deal with a form of [...] addiction causing her to become emotional, enter into a relationship with Trip, and ultimately begin to learn what it means to be a Vulcan.

Key episodes:

Archer

The four seasons of Enterprise have shown Jonathan Archer's growth as a commander. At the beginning, he is seen to be idealistic, naïve, and somewhat unsure of himself. There are episodes (most notably "A Night in Sickbay" and "Shockwave, Part II") in which his competency as a commanding officer is called into question by superior officers and fellow crew. The Xindi mission hardens Archer, making him more cautious and confident in his abilities, although he is concerned when he discovers what lengths he's willing to go to in order to save his homeworld. The fourth season sees Archer beginning to find his place in Starfleet history as the birth of the Federation approaches.