The Seeds of Doom (unrelated to The Seeds of Death, incidentally) starts in the Antarctic, when an excavation uncovers an alien plant pod. As the pod opens, infects one of the humans and turns him into a plant-like creature, I expected a run-of-the-mill monster story all set within the base. An isolated location, cut-off from the outside, with danger of death all around.
But the story actually only spends two episodes there. The base is blown up and a second pod is taken back to England, whereupon the stakes are significantly raised. Another infected human becomes an enormous monstrosity (a Krynoid) that threatens to turn all plant life on Earth against humans, and replicate itself into more man-eating monsters and take over the planet. To be honest, I preferred it when the stakes were lower, but I must admit, this one is well done.
It is a monster story in the truest sense. There’s no attempt to reach an understanding with the creature, despite it showing its intelligence. We’re left to the Doctor’s word that it is an unstoppable evil that must be destroyed, and who are we to question him? But the human face to this evil is Harrison Chase, a millionnaire plant-lover, who I was sure would turn out to be an alien himself (he’s so oddly calm and strange), but he is simply a madman who succumbs to the power of the plants.
Nevertheless, most of the characters are more memorable than usual, and even Chase’s thug-for-hire (Scorby) has a personality that almost makes you feel sorry for him, probably because he’s played by John “Boycie” Challis and gets more than two lines of dialogue. Meanwhile, the Doctor does his thoroughly enjoyable routine of calm mockery and occasional shouting, and this time does a surprising amount of physical fighting too.
It doesn’t shy away from a bit of violence, either real or implied. Chase’s sticky end in the vegetable grinder is more ‘clean’ than one might realistically expect, but it was probably a hard job to get away with what they did! Elsewhere, you have vines strangling people, giant tentacles smashing through windows and another explosive finish as UNIT calls in an airstrike to kill the creature in the nick of time. On this whole, it’s fairly good, and hasn’t aged as badly as you might expect.