Well, looks like the Doctor didn’t strand Ian in Revolutionary France. That’s probably a good thing.
But in terms of bad things, something goes wrong with the TARDIS again. The door open early, the monitor blows out, and the thing comes to a halt on a familiar planet.
Good news, everyone! They’re back on Earth, and it looks like it’s the present!
Bad news: the TARDIS and everyone on it was shrunk down to something like an inch high. If there’s more good news, it’s that all the insects they encounter seem to be dead. That’s probably for the best as that way they don’t have to pretend those bugs are moving around.
More bad news: when Ian and Susan go one way, they find a discarded book of matches. When the ground shakes badly, both of them look to hide somewhere, and Ian chooses to go inside the matchbox. He’s scooped up by an older man named Farrow, a government scientist who fortunately never looks inside the matchbox too closely and also leaves the box on the ground when he sits down for a smoke.
Now, Farrow apparently made an enemy in the form of industrialist Forester. Forester has developed a new insecticide, but Farrow found it was too potent, hence all the dead insects. He won’t OK its use, and so Forester does the only reasonable thing and pulls out a gun and shoots the old scientist. It sounds like a canon going off to the tiny people, but Ian manages to get back to the others and tells them what he saw. As the time travelers go to investigate, they get confronted by the most dangerous thing possible to things their size: a cat.