Doctor Who: Mission to the Unknown

This story is unique among Classic Who episodes. The story is one part, and it doesn't have the Doctor or any of his companions. It was meant as a teaser for the upcoming story "The Daleks' Master Plan." It is sometimes referred to as the "Dalek Cutaway."

Space Security Agent Marc Cory crash lands on the planet Kembel. He's looking for the Daleks. Well, he found them. The Daleks have formed an alliance with some other baddies, and they're going to invade Earth. Cory manages to send a warning signal to Earth before the Daleks get him. That's it! What confuses me is why there is an unrelated story between this one and "The Daleks' Master Plan." Shouldn't they have aired it immediately after this one? Why not just make this the first episode of that serial? See you in a month, Daleks. We have to stop in Troy first...

THE RUNDOWN

Doctor: First (does not appear)
Companions: Vicki, Steven (do not appear)
Episode: #19, "Mission to the Unknown," one part
Adversary: the Daleks
Classic Lines: Daleks: "Exterminate!" (Yep, they always say this. Classic!)
Tuck This Away to Impress Your Friends: This is the only episode that doesn't have the Doctor or any of his companions.
Next Up: "The Myth Makers"