There’s a moment in this episode where Romana says a narcotic drug was destroyed and no one used it anymore. Except, the TARDIS pops around time and space, and unless she and the Doctor determined exactly what year it is when they got off the TARDIS, how does she know that this drug was destroyed a long time ago?
I probably shouldn’t think about that.
So, at some point in what is probably the future, a scientific survey ship and a space-based passenger liner crash into each other. The two ships more or less merge because one was going into warp or something, and that sure isn’t stable.
That would be about when the TARDIS appears.
Now, it does seem as if the reason the two ships hit is because the liner’s co-pilot was waaaaaaay too relaxed. The co-ordinates were off, and he didn’t care.
If you guessed he’s on drugs based on what I wrote above, you’d be right.
Anyway, the Doctor, Romana, and K9 get off the TARDIS and Romana suggests they shouldn’t interfere because that would be rude or something. The Doctor, meanwhile, insist they should because it is what he is best at. And so, they head off to the liner’s cabin where the survey captain and the liner’s ;pilot are arguing, and the Doctor passes himself off as coming from an insurance company.
In a rare move, the liner pilot looks that up and finds the company went out of business a couple decades earlier. The Doctor does blow that off.
So, here’s the situation as things stand. Romana discovers an eccentric zoologist named Tryst who has samples of different worlds held in what Romana considers a rather primitive form of interdimensional stasis, but one world catches her eye. Tryst’s female assistant Della doesn’t want to think about that one because she lost someone close to her there when Tryst went there to do whatever it is he does. Romana will later look into things and something will fly out and sting her.
As for the Doctor, he first follows the co-pilot around with K9 to see the guy get his drugs, and after using the sonic screwdriver to open the secret drawer, realizes why this guy just don’ care ’bout no rules and precise numbers. Then the co-pilot is attacked by something and dies. The Doctor will later be knocked out by a stun gun fired by the drug dealer, whose face we don’t see, and then later he and the pilot will have K9 blast through a bulkhead to try and separate the two ships.
But there’s some kind of angry critter back there.
They might want to close the hole back up again.