“Regeneration” is episode twenty-three of season two of Star Trek: Enterprise.
A craft lands in the Arctic Circle and three scientists are examining the wreckage of something that has crashed. Something large. The woman, Rooney, brushes away some snow. Revealing a Borg drone under the ice. They identify it as a humanoid of unknown species and the leader, Drake, tells someone to contact Starfleet. Rooney thinks there’s a lot more and then stumbles across another drone.
In the lab, Moninger and Drake are looking at a separated arm that Drake says was integrated directly into the circulatory and nervous systems, even though it’s mechanical. Moninger met a Vulcan scientist with a prosthetic arm, but nothing like this. The two humanoids are of different species, too. Drake wants the findings transmitted to Starfleet and is talking to Rooney about an alloy when they hear a noise. A mechanism on the arm has activated.
Moninger is showing Drake mechanisms that are repairing the cells that he believes is a form of nanotech. The aliens have thousands and they’re fixing the mechanical components and damaged tissue. Moninger suggests moving the bodies to cold storage; Drake is concerned they might be damaged and declines. Moninger is worried what might happen. Drake says there’s no reason to assume the species is hostile. He really should. Drake wants to see what will happen if they regenerate. Hint: bad things.
Drake startles Rooney outside. They are looking at something with a warp signature. Another brings Moninger a flask and asks if he will be okay on his own. Moninger says he will. He is wrong. One of the drones’ vital signs start up. And the drone activates. The other two outside hear something as the lab is shot up. Inside, Moninger is down and being assimilated. The other drone is active.
Admiral Forrest is informed about a problem with the team; nothing has been heard from them in three days. At the site, there are no drones and no scientists.
Captain Archer shows images of the Borg to his staff. It’s believed they abducted the research team. Reed points out they’re a long way from the Arctic. It seems the expedition’s transport was spotting leaving orbit at warp 3.9 – in a warp 1.4 capable transport – and heading their way. They’ve been ordered to stop it. Reed heads to see Phlox for advice on combatting the aliens. Phlox doesn’t seem as offended by the cybernetics as Reed is. His opinion will change.
The captain is reading in his ready room when he’s called to the bridge; a distress call has come in from a Tarkalian freighter. Heading shows the transport attacking the freighter. The captain tells the transport to stand down from their attack. The Borg’s response is to open fire. In a previously unarmed transport. There are nine, erratic, biosigns on the transport. Its weapons are disabled but as there are two biosigns on the freighter, it’s allowed to warp out.
Phlox briefs T’Pol and the captain on the Tarkalians; nanoprobes have infiltrated them and they’re being transformed. T’Pol thinks it’s likely the humans are being similarly affected. Phlox can’t remove the nanoprobes surgically, just slow their progress. T’Pol suggests isolating the Tarkalians. Phlox doesn’t think that’s warranted – he’s wrong – but the captain wants a guard posting.
The captain is reading ion his ready room again when T’Pol arrives. There was something familiar about this and he tracked it down to a speech Zefram Cochrane made 80 years ago. About how cybernetic creatures from the future tried to stop his first warp flight but were stopped by humans from the future. T’Pol points out Cochrane was known for his imaginative stories and intoxication. Archer says no-one took him seriously and he recanted it a few years later. But he said that the ultimate goal was to enslave the human race. What if the goal is the same and they’re heading back home for reinforcements?
In sickbay, a Tarkalian starts coming around. Then attacks, knocks down the guard and injects Phlox before they both leave. The doctor is hearing the Borg Collective when he’s woken up. He scans himself and says he’s been infected. And warns them not to get close.
The Borg are constantly upgrading and there are two loose on Enterprise, plus an infected Phlox. The captain wants to save the research team. An overly optimistic hope. The Borg are never mentioned by name, and this is one case where the viewer knows rather more. When the Enterprise later encountered the Borg in “Q Who?” the Borg were much, much closer to the Federation than they would be in Borg space.