The Time Lords have sent him to Spiridon, described as "one of the nastiest pieces of space garbage in the ninth system. The vegetation is more like animal life than plant, creatures that are hostile to everything including themselves, and a climate that changes from tropical during the day to subfreezing in the night."

That analysis was given by one of a trio of Thals who rescue the Doctor from near oxygen starvation. They initially don't trust him, but they team up to fight against Daleks planning to master invisibility, that's a potential ten thousand Daleks who will conquer the galaxy if they succeed. Of the Thals, Tarron is the cautious leader, Vaber is impatient, wanting action, Codal is scared but courageous, and Latep, has a goofy look on his face when he sees Jo and is smitten.

The Doctor plays counselor to the people he met during his first incarnation. He gives the self-doubting Codal a "tutorial on bravery." "Courage isn't just a matter of not being frightened. It's being afraid and doing what you have to do anyway." When Tarron is worried that his lover Rebec being part of the team would affect his command decisions, he is told: "The business of command is not for a machine. The moment we forget we're dealing with people, we're no better than the machines we came to destroy. If we start acting and thinking like the Daleks, the battle is lost." And to the follies of glorifying war: "Be careful how you tell that story [of war]. Don't make war sound like an exciting or thrilling game. Tell them about the fear, otherwise your people might relish the idea of war. We don't want that." No, and neither should we.

The jungle set is really well-realized, as well as the design of the exotic plants. However, the creatures' eyes on the Plane of Stones are clearly lights flicked on and off.

Bernard Horsfall (Tarron) would play Goth in The Deadly Assassin, and Prentis Hancock's Vaber is a warmup for his role as Salamar in Planet Of Evil. Roy Skelton has double duty providing Dalek voices and playing the friendly Spiridon native Wester.

This is a fond tribute to the very first Dalek story, and that's what makes this story successful. There are repeated references and themes to the first Dalek story, beginning with his mention of how he, Barbara, Ian, and Susan, helped the Thals against the Daleks. Another is the Daleks disabling their victims rather than killing, and there are many more--see how many you can find. And since Episode 3 is shown in black-and-white (guess what the BBC did with the colour original?) that's a reminder of how old William Hartnell stories were seen.