The Fourth Doctor gets a brand new companion and someone’s carved a familiar face on Mount Rushmore
At an unknown time, on an unknown planet, an as yet unnamed tribe is being shitty to their only female tribes person, Leela. Upon closer inspection, the tribe, who call themselves the Sevateem, are perhaps not what they seem: their leader sits upon a throne that looks suspiciously like it came out of a spacecraft and their shaman is wearing bits of a spacesuit. Their behaviour, on the other hand, is straight up savage and the unfortunate Leela is banished for questioning their beliefs.
When an unaccompanied Doctor arrives on the planet, he is mistaken for “The Evil One” and nearly sacrificed. As fortune would have it, though, the equally unwelcome Leela pops round and saves him, and they escape into the jungle. Alas, it is populated by invisible phantoms, surrounded by a makeshift time barrier and guarded by a mysterious force with a familiar face that purports to have abducted the god of the tribesmen, Xoanon.