After weeks searching the Delphic Expanse, the crew is led to a mining colony where they hope to find a Xindi worker, who can lead them to the mysterious species' homeworld.
The crew receives a distress call from a Vulcan ship lost in the Delphic Expanse, only to discover that its crew has been driven insane. T'Pol begins to suffer the same effects as her old crew.
Hoshi is lured to a deserted planet by a powerful telepath, who promises to help them locate the Xindi. Enterprise investigates another anomaly-creating sphere.
Captain Archer must decide whether or not to trust Earth's greatest enemy when the crew discovers a Xindi colony that is manufacturing a vital component of the Xindi weapon.
An encounter with an anomaly leaves Captain Archer unable to form new, long-term memories. He awakens to discover that 12 years have passed, Earth has been destroyed by the Xindi, and a small colony of humans is fighting for survival.
Enterprise discovers a colony of humans, taken from Earth when the West was young, living in the Expanse. Captain Archer discovers that the humans have overthrown their former captors.
An accident in engineering leaves Trip in a coma. In an attempt to save his life, Phlox creates a mimetic symbiote -- a rapidly-aging clone of Trip who will lives out his lifespan on board the ship in only 15 days.
Daniels returns to Enterprise to inform Archer that three Xindi Reptilians have been discovered on Earth in the year 2004. Archer and T'Pol are sent back in time to stop a plot to develop a second weapon to wipe out the human race.
Enterprise is hijacked by a group of religious zealots who worship the sphere builders, and who plan to use the ship to destroy their ideological enemies.
An Andorian ship under the command of Shran arrives in the Expanse with promises of helping the crew find the Xindi weapon. But the Andorians may have their own motives.
After capturing Degra, the engineer behind the development of the Xindi weapon, the crew engages in an elaborate hoax to convince him to reveal its location.
Tensions on Enterprise run high as the ship travels to Azati Prime, and Reed's relationship with Major Hayes comes to a head. When the ship finds an alien inside an expanding anomaly, Archer makes a frightening discovery about the sphere builders.
The human crew must be placed into a comatose state to survive a trip through a deadly region of space, with only Phlox, T'Pol and Porthos left to man the ship.
The Enterprise crew finds a crashed Xindi Insectoid ship, where the only survivors are the crew's soon-to-hatch offspring. The crew suspects alien influence when Archer puts the ship and the mission at risk to save them.
The crew finally finds the weapon that will soon be launched to destroy Earth, and Captain Archer prepares to sacrifice himself to destroy it -- only to be pulled into the future by Daniels and told that he must survive and make peace with the Xindi.
As the crew tries to recover from a devastating battle with the Xindi, Captain Archer must decide whether or not to cross an ethical line for the mission to have any chance to succeed.
While the crew continues to repair Enterprise, Captain Archer invites two high-ranking Xindi onto the ship to show them evidence that they are being manipulated into destroying Earth. Trip struggles to deal with the death of his loved-ones.
On their way to a vital meeting with Degra, the crew encounters a duplicate Enterprise populated by their own descendants -- who warn them that the subspace corridor ahead will throw them more than 100 years into the past.
Archer is brought before the Xindi Council to present evidence they are being manipulated by the sphere builders, whom they revere nearly as gods. A team from Enterprise infiltrates one of the spheres to try and access information.
The crew and their new Xindi allies race to stop the Reptilians and Insectoids from unleashing the weapon on Earth. Major Hayes leads a unit to rescue Hoshi, who the Reptilians are forcing decrypt the weapon's launch codes.
Archer makes his last stand against the Reptilians as the Xindi weapon hurtles towards Earth. T'Pol and Tucker lead the crew on a mission to destroy a key sphere in the hopes of breaking the Guardians' hold on the Expanse.
