Season 20, Episode 124 - "Arc of Infinity"
3 January, 1983
Shielded by a collapsed star lurks a malevolent presence, an alien consisting of pure anti-matter. Its intention? To bond with a Time Lord and so cross over into this dimension through the Arc of Infinity — the gateway to all dimensions. The chosen Time Lord is the Doctor. To avert disaster, he is recalled to Gallifrey before the collision of matter and anti-matter leads to the destruction of all dimensions.
