When in doubt, throw the Doctor into a jungle with Daleks. Works every time.
Short Synopsis
After escaping from the Master’s mess in Frontier in Space, the Doctor and Jo crash-land on Spiridon, a planet full of invisible natives, deadly plants, and — surprise — a secret Dalek army waiting to be defrosted. Naturally, it’s up to the Doctor, Jo, and a squad of Thals to stop them.
Extended Storyline
Picking up right where Frontier in Space left off, the Doctor collapses from his run-in with the Daleks. Jo, being the practical one, puts him in the TARDIS medical unit and then promptly wanders off into a jungle that makes the Amazon look like a window box.
This jungle is not friendly. Plants squirt out poison gas, the wildlife wants to eat you, and oh yes — there are invisible creatures known as Spiridons. Because apparently regular monsters weren’t enough, we needed see-through ones.
Jo soon stumbles upon a squad of Thals — yes, the same blonde space-heroes from the very first Dalek story. Turns out they’re still fighting their eternal war with the Daleks, and someone thought a jungle expedition was a good idea.
The Doctor, once revived, teams up with the Thals and quickly discovers the Daleks’ big plan: they’ve got an army of 10,000 Daleks frozen in cold storage, waiting to be thawed out for galaxy-conquering fun. It’s like someone left an army in the freezer next to the peas.
Cue the usual shenanigans: sneaking into Dalek bases, escaping from Dalek bases, getting captured, escaping again, rinsing and repeating. Jo befriends one of the Spiridons (because she has a knack for befriending the unfriendliest locals), and the Thals display their usual brand of heroic but not-very-bright courage.
The climax sees the Doctor and friends unleashing an ice volcano (yes, that’s a thing) to bury the Dalek army under tons of frozen sludge. It’s a bit like dumping a giant milkshake on them, only less tasty. Crisis averted, galaxy saved, and the Daleks reduced to popsicles — at least until next time.