“Threshold” is episode fifteen of season two of Star Trek: Voyager.
Tom is in a shuttlecraft at warp. When he reaches warp 7, B’Elanna says it looks good and to fire up the new engines. He engages the transwarp drive. The shuttle approaches warp 10, but one of the pylons starts to fracture. The shuttlecraft starts to break up, then Tom is sitting on the floor of the holodeck with B’Elanna and Harry watching. He’s dead.
The three retire to the galley. Every time they get close to the threshold, subspace torque rips the nacelles from the shuttlecraft. Neelix asks if he can help. Does he know anything about this stuff? No; bit he’s a quick study. Harry says it will take too long to explain and Neelix asks if he isn’t smart enough. He did spend two years as an engineer and knows warp theory.
With B’Elanna getting some biscuits, because Neelix has settled in to listen, the other two explain that they are trying to break the maximum warp barrier. Nothing in the universe can go past warp 10. It’s a theoretical impossibility. You would be travelling at infinite velocity. Very fast, as Neelix puts it. You would exist at every point in the universe simultaneously and could go anywhere instantly. Like home.
The dilithium they recently found in an asteroid field is stable at a higher warp frequency. Harry explains what happens every time they run a test. Neelix, as an example, recounts how he lost a warp nacelle in a dark matter nebula. A dark matter bow wave formed and it eventually tore the nacelle away. Maybe the same thing is happening here. Harry doesn’t think so but Tom has an idea. Maybe the nacelles aren’t being torn from the shuttle; maybe the shuttle is being torn from the nacelles. The fuselage is travelling faster than the nacelles. This turns into a discussion and a way to fix it. Looks like Neelix helped after all. Even if he doesn’t understand a word they said.
The next simulation has Tom reach warp 10, and the senior staff is shown it. The captain asks what’s next. A manned test flight, a very brief one. Then examine the sensor logs and plan for a more extended flight. Chakotay wonders if they are ready. Janeway reassures him that, over the last couple of centuries, they have used each new advance in technology responsibility. And tells Tom Paris he will be joining an elite group of pilots.
Later, the captain comes to Tom’s quarters. The Doctor is concerned and wants to let Harry do the test flight. Tom has a small chance of brain haemorrhage. 2%. Tom thinks that’s easily worth the risk. He explains that, when he was a boy, Tom’s father told him he was special and would do something significant. So did everyone else. That didn’t happen. Now it can. Yes, he is sure about this.
The shuttlecraft sets off at warp and Voyager keeps up as long as she can. When Tom hits warp 10, his transmission goes garbled and then he disappears from sensors. Tuvok doesn’t think it’s been destroyed. Then something is detected coming out of subspace and the shuttle reappears. Tom is beamed straight to sickbay.
In sickbay, the Doctor tells the captain that Tom’s lifesigns are normal. From what he can tell, he’s just asleep. Janeway asks if Tom can be woken. The Doctor doesn’t see why not. And yells in Tom’s ear for him to wake up. Captain Janeway was probably expecting a hypospray. Tom explains what happened, how he realised he was everywhere at the same time He saw Voyager looking for him and took his engines offline, and arrived back. B’Elanna arrives in sickbay; the shuttle is without a scratch and it’s confirmed he did it. The logs need downloading, but the Doctor wants Tom to stay in sickbay for a few hours. The logs describe every centimetre of the sector. Which will be highly useful.
Tom and B’Elanna are in the galley discussing the next step. Tom doesn’t like the new coffee blend Neelix has named after him. Then starts feeling unwell. Then collapses, with his veins turning black. The transporter room can’t get a lock on him, because his pattern keeps changing, so Tom is taken to sickbay the old-fashioned way.
The Doctor thinks it looks like an allergic reaction, and asked what Tom ingested. Some of Neelix’s coffee. The Doctor thinks it’s a miracle Tom is still alive. Tom is definitely having an allergic reaction. To the water in the coffee. Tom’s entire biochemistry is changing. Then he starts struggling to breathe; he can no longer process oxygen and needs something rather different. This is probably related to the experiment.
Tom’s condition continues to deteriorate, as in he’s dying. He also starts to be a bit out of it; perhaps not surprising. Then things start going a bit strange. Which is perhaps why the episode was received so badly; it tends to be classified as one of the three episodes of Star Trek ever. One thing that can be determined is that warp 10 is probably not going to be a suitable method of getting home.