10/8/2004. Storm Front, Part I — The crew of the Enterprise finds itself in an alternate version of 1944 where Germany, assisted by an alien influence involved in the Temporal Cold War, occupies the eastern United States.
10/15/2004. Storm Front, Part II — Only the crew of the Enterprise stands between an alien and his plan to escape Earth of the year 1944 and tamper with the timeline in ways that could destroy the histories of countless civilizations.
10/22/2004. Home — The Enterprise returns home for refit while its crew takes shore leave and finds that being a part of Starfleet has new meaning on Earth.
10/29/2004. Borderland — Captain Archer recruits Dr. Arik Soong — a biologist sent to prison for birthing frozen embryos left over from the Eugenics Wars — to help the Enterprise track down these genetically enhanced humans, now grown, who have incited tensions with the Klingons.
11/5/2004. Cold Station 12 — Soong and his Augments besiege a medical research facility, hoping to steal and bring to life the 1,800 frozen embryos that are stored there.
11/12/2004. The Augments — As disagreements drive a wedge between Soong and Malik, the Enterprise must stop the Augments from launching an attack that could incite a war with the Klingons.
11/19/2004. The Forge — The bombing of Earth's embassy on Vulcan brings the Enterprise to investigate a Vulcan subculture that the High Command says might be responsible.
11/26/2004. Awakening — While Archer and T'Pol are taken prisoner by the Syrrannites, the crew of the Enterprise seeks answers to why the Vulcan High Command has blamed the Syrrannites for the embassy bombing.
12/3/2004. Kir'Shara — As the Enterprise travels to Andoria to warn Shran of a possible surprise attack, Archer and T'Pol must bring a historic obelisk to the Vulcan High Command as proof of the Syrrannites' true intentions.
1/14/2005. Daedalus — Emory Erickson, the inventor of the transporter, comes aboard the Enterprise to perform a risky experiment while harboring a secret from his past.
1/21/2005. Observer Effect — Two non-corporeal aliens observe how the people on board Enterprise react to a crisis when a deadly virus with no cure infects two members of the crew.
1/28/2005. Babel One — A series of surprise attacks in a volatile region of space threatens to derail negotiations between the Andorians and Tellarites, which the Enterprise is mediating.
2/4/2005. United — Archer attempts to form an alliance in order to neutralize a threat from a common enemy, but instead finds himself in the middle of a fight to the death with Shran.
2/11/2005. The Aenar — Archer and Shran attempt to recruit an individual from a telepathic Andorian subspecies in order to combat an enemy ship piloted by remote control.
2/18/2005. Affliction — When the Enterprise visits Earth for the launch of the Columbia, Phlox is kidnapped and brought before the Klingons, who want him to find a cure for a deadly outbreak.
2/25/2005. Divergence — The Enterprise teams up with the Columbia to rescue Phlox from the Klingons, who are planning to destroy one of their own colonies to contain a deadly outbreak.
4/15/2005. Bound — An Orion captain gives Archer three Orion slave girls as a gift, but their hypnotic powers over the men in the Enterprise's crew puts the ship in danger.
4/22/2005. In a Mirror, Darkly, Part I — In the mirror universe, Archer stages a power play to take over the Enterprise — initially under the command of Captain Forrest — and diverts it deep into Tholian space.
4/29/2005. In a Mirror, Darkly, Part II — With the advanced technology of the Defiant at his command, Archer hatches an ambitious plan to take over the Terran Empire.
5/6/2005. Demons — After returning to Earth for a conference that may establish a new alliance between Earth and several alien societies, Starfleet becomes aware of a human isolationist movement that plans to derail the proceedings.
5/13/2005. Terra Prime — Terra Prime, a group of radical isolationists, seizes control of a deadly weapon on Mars and demands the immediate withdrawal of all non-humans from Earth's solar system.
5/13/2005. These Are the Voyages... — Searching for insights before making a tough decision, Commander Riker of the Enterprise NCC-1701-D looks back via a holodeck recording to the final mission of the Enterprise NX-01.
Fourth Season Recap — A capsule review of each episode, character and storyline discussion, and an analysis of the entire season overall.