In new episode "Lux", the Doctor and new companion Belinda Chandra travel to 1952 Miami, where an evil 'toon has literally ...

Although the Fourth Stage is the smallest of the four performance rooms in the building, it is, nonetheless, programmed and run with the same attention to detail given to the other spaces.

POSSIBLY the question, What is the fourth dimension? may admit of an indefinite number of answers. I prefer, therefore, in proposing to consider Time as a fourth dimension of our existence ...