The Enterprise, under Captain Jonathan Archer, sets off on its maiden voyage with a mission to return a wounded Klingon to his people.

Daniels and Archer must find a way back to the 22nd century in order to make sure history plays out as it should. Meanwhile, on board Enterprise, the Suliban have taken over the ship, but Reed, Trip, and T'Pol formulate a plan to eject the aliens.

The remnants of an alien ship and two frozen cybernetic bodies are uncovered in the arctic by a research team. These aliens soon thaw out and flee Earth, taking the research team with them. Starfleet orders Enterprise to find them, but the crew aren't prepared for just how dangerous these aliens really are.

Once the NX-01 finally returns to Earth, the weary crewmen face repercussions of their journeys, both positive and negative.