Blake's 7 1980 S03E10

Episode: Ultraworld. The Liberator detects a mysterious spiky metal globe floating in space. Avon deduces that it is an artificial planet, but can't raise any communication. Then Cally disappears - apparently abducted inside the "planet". As well as affecting minds, this "Ultraworld" turns out to be capable of stealing them - and using the zombified bodies of space travellers to trap others. But the crew must ultimately face the menace that rules from the centre of the Ultraworld.