“Vis à Vis” is episode twenty of season four of Star Trek: Voyager.
The Doctor materialises on a holodeck where Tom is working underneath an old car. He hoots the horn to get Tom’s attention; an auditory exam to test Tom’s hearing to see if he did hear the Doctor when he asked Tom to meet him this morning. Tom forgot. Sickbay training may be voluntary but Tom has spent hardly any time there in the past few weeks. When the Doctor tries to find him, he’s always on the holodeck. Tom says they haven’t had any serious injurie4s. That’s not the point; when an emergency happens, he needs to be repaired. Tom hasn’t been keeping up with his medical texts. Tom claims he has just completed a complicated surgical procedure. On a car. He explains what it is. The Doctor thinks the car is dangerous. It might be just what Tom needs to get him back to sickbay.
The captain summons Tom to the bridge. Harry says another spatial distortion is forming, as if space is folding in on itself. A ship appears with one occupant. Tom suggests it looks as if it has a coaxial warp drive, a hypothetical propulsion system that folds the fabric of space, allowing a ship to instantaneously travel huge distances. A shock wave hits Voyager; Tuvok says the warp drive is overloading. According to Tom, a coaxial drive explosion could theoretically collapse space in a radius of a billion kilometres.
They can’t beam the pilot out and the coaxial core is breaching. Tuvok suggests leaving; Tom suggests using their won warp drive the stabilise the other ship’s. The captain authorises this and it works. Then the ship hails; the pilot is okay but his ship isn’t. They may be able to help. Tuvok and Janeway head to greet the pilot, Steth, as he’s beamed aboard. Steth says he was so eager to test his new engine that he pushed it beyond its limit.
Tom heads to see Chakotay. He wants to help Steth repair his ship. Chakotay points out that the Doctor has said Tom hasn’t turned up for work. He wonders if there’s something wrong, because Tom’s heart doesn’t seem in it currently. Tom thinks he needs a change of pace. Chakotay says that Tom is a different person to the one who came aboard four years ago. He wouldn’t want Tom to ruin that. But he does agree to let him help Steth.
Steth is telling stories to Tom but, whilst Tom is turned away, Steth briefly transforms into an alien woman of a different species. Steth suggest Tom come back with him to test a new warship. Tom says he has responsibilities. And B’Elanna would be furious. Then remembers something. He was supposed to meet B’Elanna in the mess hall. She is not happy. She’s also concerned about Tom’s recent behaviour, and he gets defensive. Meanwhile, Steth is transforming again and asks his computer to do a DNA stability analysis.
Tom is taking Steth to the holodeck. He had an idea for fixing the coaxial drive. A carburettor. He explains how it would work and Steth thinks Tom has solved it. He says Tom is lucky to be stationed on a ship like this. Tom doesn’t sound enthused. Once again, whilst Tom isn’t watching, Steth briefly transforms. As he leaves, he swipes one of Tom’s tools. In Seven of Nine’s cargo bay, he also downloads Tom’s files. She tells him he’s not authorised to be there.
On Steth’s ship, Tom is packing stuff away when he finds the tool Steth swiped. According to Steth, he needed it to check Tom’s DNA. Good news; they’re compatible. Steth seizes Tom by the throat; he transforms into Tom’s appearance and vice versa. Then Steth shoots Tom.
Steth, who is now taking Tom’s place on Voyager, sends his ship away with Tom on it. Though he might have got Tom’s files, he doesn’t have Tom’s knowledge, and starts behaving what appears to be erratically. On a couple of occasions, Steth manages to cover this up, but he’s really acting too strangely. Meanwhile, Tom, no longer looking like Tom, needs to get back to Voyager. Tom had been feeling out of sorts with life on the ship; losing it, and his appearance, makes him realise just what he’s got.