49. The Fourth Doctor Enters the Matrix
From: "The Deadly Assassin"
Premiere: October 30, 1976
The Fourth Doctor (Tom Baker) is summoned to Gallifrey in order to help untangle a political plot involving renegade Time Lord the Master (played by Peter Pratt, and gruesomely deformed here) and a scheming politician. Operating solo for the first time ever and framed as a would-be assassin, the Doctor takes a prescient (and decidedly trippy) excursion into the Matrix, Gallifrey's global neural net, in which thought patterns become virtual reality.