Part 1

E1

The episode is based upon the stories "The New Accelerator" and "The Queer Story of Brownlow's Newspaper"

Part 2

E2

The episode is based on the stories "The Crystal Egg" and "The Remarkable Case of Davidson's Eyes"

Part 3

E3

The episode is based on the stories "The Truth About Pyecraft" and "The Stolen Bacillus"