What a fun episode! The beginning is a little slow but it quickly picks up the pace. We've had space viruses before, but never one quite like this.

A small detail but one I appreciated nonetheless was the secretary not questioning the Doctor's name at all. As a nonbinary person with many nonbinary friends, many of whom use nouns as names, I like the idea of that becoming ordinary in the future.

I already adore K9. I love how he and Leela immediately got along the moment they realised the other isn't a threat. They have a surprising amount of things in common. (And who would have expected the Doctor to have a dog leash in his pocket? I'd love to know the backstory for that!)

I think my only gripe with this story is the repetition of Leela being immune because she's a "savage". She's not any less intelligent than the other humans simply because she wasn't taught all the things they were! It's also a return to the thing that annoyed me the most in the early Three and Jo era, where the Doctor looks down on his companion and doesn't seem to actually *like* her. I have gotten a bit of that vibe with Leela but have managed to ignore it so far. I hope this changes in future episodes.