CONTACT... HAS BEEN MADE.
A primitive-looking space shuttle wobbles through the fakest looking space you’ve ever seen and then flies into into an even faker-looking asteroid field and through a milky-looking space cloud with lightning inside. The astronauts aboard it get infected with an intelligent virus and carry it to a pretty fake-looking base on Titan, the real-life moon of Saturn you dummy. Their spacesuits however aren't too bad.
The first episode has a scene several seconds long of the Doctor's elbow for some reason. Being sick with the virus makes you grow fish scales and wispy gray feathers around your eyes and maybe some fuzz on your hands. The Doctor and Leela fly the TARDIS into the same space cloud and the Doctor gets infected too. The Doctor uses his duck call and demands that breeding from his nucleus begin and we all feel a little uncomfortable, right?
They take the Doctor to an asteroid hospital that looks like a paper skyscraper that got wadded up and hung on a wire. While there they meet Professor Marius, a man who built himself a robot dog named K-9. The infection slowly begins to spread to the hospital staff and K-9 shoots one infected guy right in the crotch. The Doctor and Leela get cloned and shrunk down to microscopic size and injected into the real Doctor. Inside the Doctor’s head, Leela inside gets attacked by some phagocytes (say it out loud and giggle, go ahead) while the real Leela outside holds off the infected hospital staff.
Much faffing about takes place in the back half of of this story until they discover an angry hissing lump of coal in Tom Baker’s brain, which explains a great deal about him, if you think about it. The angry lump of coal gets out of Tom's head and is enlarged into a midget-sized angry wheezing prawn (that not even Baker can take seriously), probably because the angry lump of coal wasn't ridiculous enough - it certainly wasn't much to look at. The angry prawn wants to go back to Titan to breed without Tom. The infected people get the giant virus-prawn back to Titan where it lays some pretty gross-looking eggs so the Doctor blows it up - not just Titan Base but the entire fucking moon apparently - awesome! You don't see the Doctor do that too often. In the end K-9 leaves with the Doctor and Leela.
Not terrible, not great, and not really much to write home about other than being the first K-9 story. I'd call it a "filler" story, except back then there were no huge season arcs to muddy things up so technically, every story was "filler," as "fill up the season." Still decent enough to waste a couple of hours on, if you keep your expectations low.
It was so bad that the foreknowledge of it caused the deterioration of William Hartnell's health.