“Similitude” is episode ten of season three of Star Trek: Enterprise.
The crew are gathered and Captain Archer is holding a funeral. For Trip.
The episode then goes back two weeks. Trip and T’Pol are doing neuropressure; Trip is talking about a modification he could do that would make running at warp 5.0 smoother. He also doesn’t think advanced neuropressure is as bad as T’Pol suggested.
In the engine room, Trip tells the captain they’re all set. They need to go to warp 4.9 to get the plasma hot enough. When they get up to warp 5, everything is running smoothly. Then they hit a problem and can’t drop to impulse. Trip has to get on top of the reactor to shut it down, then an explosion blasts him across the room.
Enterprise drops out of warp; T’Pol says they are in a polaric field, which is probably what caused the problem. Hoshi says minor injuries are being reported. But Trip has been taken to sickbay. T’Pol is examining the damage when the captain arrives. Nucleonic particles flooded the manifold, causing the injector to flare. If Trip hadn’t managed to shut down the reactor, there could have been a breach. T’Pol says the damage is significant and could take weeks to repair. Trip will have his hands full. Archer tells T’Pol she will be supervising. Trip is in a coma with extensive neural damage; he may not survive.
In sickbay, Phlox tells the captain Trip’s condition is unchanged, but he wants to show the captain something. A Lysarian desert larva. It secretes a dermal suppressant Phlox uses on cuts and bruises. But is has another use. If implanted with the DNA of a species, it rapidly replicates that species’ lifecycle. A clone is born, grows old and dies in approximately 15 days. Few know of this. Phlox can grow one and then harvest its neural tissue to transplant into Trip. It might not work, but it might be Trip’s only hope of survival. They will wait until the being reaches Trip’s physical age, then excise the tissue with no discernible side effects.
T’Pol arrives in the captain’s ready room with a sample of a substance that’s accumulating on the hull. It took multiple plasma rifle hits to dislodge. She lists what they know about it. It’s also highly magnetic. So far, the danger to the ship seems negligible. T’Pol also wants to talk about what Phlox suggested. The captain approved the procedure. T’Pol asks if he’s aware the Lysarians banned the procedure; it’s growing a sentient being for the sole purpose of harvesting its tissue. The captain is aware of the ethics. But they are in the Expanse and they have their mission. Earth needs Enterprise and Enterprise needs Trip.
The procedure is done, but particles are building up on the hull. Phlox shows Archer and T’Pol the newborn; he’s going to keep the child in sickbay. And he wants to name it. T’Pol and the captain both look uncomfortable about this. It turns out that this Trip has Trip’s memories; Phlox tells the captain that this might be an important discovery, genetic memory in humans.
The clone – Sim – is asking questions about why he’s there and where his parents are. So the captain takes him to sickbay and shows him Trip, explaining what will be done. However, they are running out of time to get out of the cloud; they need to do it before Trip is healed. Sim is definitely attracted to T’Pol, which suggests that Trip may be as well, and then there are a whole bunch of ethical considerations, more serious than were originally thought. Which are overruled by the need to save Earth.