The Kidnapping of Dr. Watson (The Adventures of the Elderly Sherlock Holmes, Episode 8)

Sudden darkness. Hands grabbed Watson. He thrashed about wildly, but it was all in vain. A violent blow to the head.
When he regained consciousness, he found himself in some sort of cell. But where exactly was he? Only the chimes of Big Ben thundered loudly in his ears. Yet why had they brought him here? There was no sign of the perpetrators anywhere.
Biting January cold, hunger and thirst pushed him to his limits. Would his friend Sherlock Holmes find him in time?