“Time and Again” is episode four of season one of Star Trek: Voyager.
Tom is handing over to another helmsman, telling her that there is a red dwarf system coming up and that they don’t know if there are any M-class planets yet. He then heads over to Harry and asks if he’s ready. No; Harry wants to run a diagnostic. Tom thinks Harry is making a big mistake. Can’t he see what’s going to happen? They are the only humans around and people are going to start pairing off. If they don’t get to the Delaney sisters in Stellar Cartography first, someone else will. Harry has a girl back home – Tom has five. Harry plans on seeing his again. When asked yes, he hopes she’s going to wait. Tom tells Harry to let her go, let her have a husband, kids, a good life. They can have the Delaney sisters. They come as a pair; a double date or no date. Besides, he told them all about Harry. What Tom told them wasn’t true but how are they going to check?
Then the ship shakes as Janeway and Neelix come onto the bridge. Tuvok says it’s the leading edge of a shockwave. In her quarters, Kes jolts awake. There’s a debris cloud in the red dwarf system they are approaching that appears to be the source of the wave. Tuvok has detected differentially charged polaric ions; which means a massive detonation. Neelix isn’t familiar with any intelligent lifeforms in the system. Kes arrives on the bridge, because she had to know. Tom says there is an M-class planet but all vegetation on the planet has been destroyed. There are no satellites or spacecraft in orbit and, when asked about lifesigns, Kes murmurs ‘None’ before Tom confirms this. Chakotay has discovered artificial waterways of a global aqueduct system, so there used to be people down there. Janeway plans to beam to the planet – because where else would the captain go than the aftermath of a planetary disaster? – and wants Tom, Tuvok and B’Elanna – promoted to chief engineer in the previous episode, “Parallax” – to come with.
The planet is dead, seared, a chain reaction in subspace vaporised anything organic. Caused by a polaric detonation. A Romulan research colony on Chaltok IV was nearly destroyed by polaric energy, which led to the Polaric Test Ban Treaty of 2268. War is the initial thought, but there are conduits that were apparently the source of the explosion. The entire civilisation ran on polaric ion energy.
On the ship, Kes is weeping. It seems she saw the disaster. She saw everyone burn. Neelix thinks it was Kes’s imagination, but no; Kes replies it was almost telepathic. There were rumours that Kes’s ancestors had unusual mental abilities, and Kes always believed them.
On the planet, Tom is examining a timepiece that stopped at the moment of the explosion. Then the gloom lifts and he hears children. No-one else heard it. Then it happens again, and this time Tom sees people, until Janeway brings him back. B’Elanna scans Tom and discovers temporal flux; Tuvok states the chain reaction has shattered subspace. Janeway contacts Voyager, asking to be beamed up, but she and Tom end up in the past before it happens. Causing a child to scream, because they appeared out of thin air.
After speaking to what would appear to be a guard, who believes they are from out of town, not demons, Janeway asks about a clothing shop – there uniforms don’t fit in. Tom spots the same timepiece he saw earlier/later in a window, and speaks to the one selling it so that he can determine how long they have. The world will be destroyed sometime tomorrow.
Harry is explaining about what happened, and B’Elanna takes over. Most shockwaves dissipate into the future; this one dissipates into the past. There’s no way to identify how far back it goes. Tuvok is certain that the captain will activate a subspace beacon. to help. Once they know where and when, they will widen the subspace fracture at that point. Although, they don’t know how yet.
The Doctor is scanning Kes. Is something wrong? Yes, terribly wrong; her brain is not on file. Kes and Neelix explain they are not part of the original crew. No-one asked for their medical histories on arrival, because that would be the ship’s doctor’s job. The EMH’s job. If anyone had bothered to tell him. Oh, and there’s also the crew of another ship that was destroyed. The Doctor wants to talk to Janeway; failing that, the highest-ranking officer who has not disappeared. Meanwhile, Kes has a lovely brain and should drink plenty of fluids. Everyone should drink plenty of fluids.
Tom and the captain have changed and Janeway has activated a subspace beacon. However, the Prime Directive states they cannot interfere with the natural chain of events. They have no idea what the consequences are. Even though the natural chain is mass destruction. The child who screamed when they appeared is following and checking up on them. Until Tom scares him off; they are demons, they eat children and Tom is hungry. Tom also suggests they could use polaric energy to get back. At the power plant, a demonstration is going on.
Voyager has discovered a way of widening a fissure, but it doesn’t work for long. And there’s only a limited amount of time before the civilisation goes boom. Janeway realises something, because of time travel – such episodes have a tendency to be confusing – and starts being more proactive.