The air was musty, as if something malevolent had crawled in there a million years ago and given birth to shadows and silence and dust.

And then, perhaps for the first time in centuries, a faint echo ran through the corridor; a sound like distant drums, or perhaps a thunderstorm far away across a black sea. The air in the corridor swung apart like a grimy curtain to reveal a large blue box with a flashing light on top. Momentarily the thunder crashed overhead, as if something infinitely heavy had come to rest.

DOCTOR: Sometimes I think that I am a Doctor of no brain at all.

The moment the doors of the blue box opened, and a small, rather exuberant gentleman in a gaudy pullover, tartan trousers and brown corduroy jacket emerged, the atmosphere changed completely. Perhaps it was the white Panama hat perched upon his head like a nesting bird; perhaps the fact that beneath its brim, like two large, round eggs, his eyes were bright and full of joyful intelligence. Whatever it was, the sum of all the individual details added up to a personality shining with the conviction that, whatever the situation, whatever the galaxy, it could be grasped as firmly and immediately as the crooked handle of his umbrella.

Twirling the umbrella like an old-fashioned propeller, the gentleman looked around, wide eyed, as if he couldn’t believe his luck in landing exactly where he had. A corridor! Yes, but what sort of corridor? What was it a corridor in? Where did it lead? And what adventures were lying in wait for him at either end?