Fun Fun Fun Fun Fun Fun Fun… I think this episode is a ton of fun.

The plot such as it is involves the Doctor noticing some sci-fi anomalies surrounding a hospital, so checks himself in. Here he meets trainee doctor Martha Jones, just in time for the hospital to be transported onto the moon. This is due to the Judoon, some interplanetary police for hire, who are searching for a criminal in the hospital, but as they have no jurisdiction on Earth, had to transport the hospital onto neutral territory, the moon in this case. The hospital is in a forcefield, so has its own atmosphere; however there is a finite amount of air, so the oxygen is running out. The Judoon search for an alien, which is a problem for our alien hero. This becomes more of an issue because the villain is a Plasmavore, who drink the blood of their victims. Once they drink the blood of their victims, they take on their genetic properties, allowing the Plasmavore to pass as human. The Doctor has to not only trick the Plasmavore into getting captures by the Judoon before the oxygen runs out in the hospital. He also has to stop an energy blast going off, hastily made from an MRI machine, that will not only kill everyone on the moon, but also half the population of the Earth.

This episode zips along at a nice, breezy pace. The dialogue is fun, but never undercuts the multiple threats in play here. The oxygen running out in the hospital means there is a ticking clock to events, increasing the sense of tension and urgency within the episode.

Anne Reid as the Plasmavore is having fun and makes for an interesting villain. Her chemistry and banter with the Doctor is a delight too.

The Judoon are both a fun design and a fun secondary antagonist for the episode. They aren’t villains; they’re just idiotic thugs with police powers, who just single-mindedly follow their protocols. This means they keep getting in the way, and because they’re looking for an alien they become a force for the Doctor to constantly need to avoid.

As good as all these elements are, the main draw of this episode is Martha Jones. I really like Martha in this episode. She’s instantly likeable, smart & perceptive. She’s willing to take risks, and proves herself a worthy sidekick for the Doctor here. I also like that she has her own life going on. She has a messy but relatable family dynamic. She has aspirations, wanting to become a doctor herself. I personally think that Martha gets the best introductory episode out of the 3 main RTD era companions, and she’s setup so well for the rest of the series.

This isn’t an all-time classic by any stretch. But as a light, enjoyable episode of television to ease you back into a new series, and as an introduction for a new companion, it’s really frickin’ good. Also did I mention that it’s fun.