2. The Green Death
Got a friend who's a bit of a hippie? The Green Death is probably the perfect way to introduce them to Doctor Who. In fact, they'd probably like all of Pertwee's era, where environmental issues were really pushed to the forefront. Sure, the maggots are a bit crap (no one's arguing against that), but the entire episode has a surprisingly nuanced approach to the ethical issues here. Essentially, the plot boils down to the fact that there's this oil refinery spewing toxic green sludge that seems to cause some rather unpleasant mutations. There's an inevitable confrontation between the greedy corporations and the idealistic environmentalists, and it plays out quite effectively in the story. And of course, there's the giant maggots. Never forget the giant maggots.