Before you read this chapter, may I just say it is not - and never has been - my intention to give the impression that I am a student of theology, so if I've made mistakes with the belief system please forgive me, I mean no offence.

From John's point of view it was quite amusing to see Sherlock frantically poring over religious tomes. And it was still more amusing to see how disgruntled he got when John didn't seem to be taking him seriously.

"Pah!" the younger man flung his hands up in disgust. "Islam doesn't teach the existence of ghosts – the closest to their beliefs would make us Jinni."

"Oh, then would I be the 'Jinni with the light brown hair'?" John had chuckled, laughing even harder at Sherlock's puzzled look. "Don't tell me – you've never heard of it even though it's Mrs Hudson's favourite song and she's forever playing it on that out-of- tune piano in her living room."

Sherlock reached for another book, and then another, while his friend wandered off into other rooms in search of something more interesting.

And he found his 'something more interesting' in a small back room, where some extremely old hand bound books were being kept in splendid isolation from their peers. In an instant he was back with his friend.

"I'm assuming you have found nothing worth noting." It was a statement not a question, and Sherlock threw him a dirty look before returning yet another book to the shelves.

"Buddhism recognises ghosts, though I do hope no one tries to lead us to the light through chanting and prayer."

John choked a little at that.

"And," The other continued, "Both Hindus and Animismists..."

"Who?"

"Tribes that follow the doctrines – if you can call it that – of Animism."

"Oh." John looked no more enlightened that he had before Sherlock's explanation.

"Yes, well. They both believe in the existence of ghosts, and I'm sure you will enjoy the irony of this – Hinduism teaches that they are people who have died before their time, and Animism that they are former tribal members who have become guardian angels."

The doctor's eyes lit with mirth.

"I would love to be able to tell Anderson and Donovan that we're guardian angels!"

"Guarding London from their incompetence?"

"But only on one night a year? Don't think it'll quite work like that." John deliberately didn't rise to Sherlock's usual bait about Scotland Yard's lack of ability to solve crime.

"However we are people who have died before their time."

"That we are." There was a thoughtful tone to John's voice.

"What?"

"Well, I was wondering what the historic precedent was for this."

Grey-blue eyes widened comically.

"Precedent?"

"Yeah," Motioning with his head for the other man to join him, John moved back towards the small room that he had found. "You see, there's a whole room here full of books on paranormal activity and the supernatural."

Sherlock looked around interestedly.

"No one's been in here for months, if not years." He commented.

"I imagine this is one very well kept secret, with access limited to a few – I dunno – paranormal scholars?"

"And judging by the CCTV in the room they don't want the contents being read by the wrong people." Leaning against a table with his fingers steepled in front of his lips. "I wonder what they have to hide."

Whirling about, Sherlock scanned the books, walking slowly along the old fashioned heavy mahogany shelves before reaching up and taking down one of the largest tomes. John peered over his shoulder.

"Strange and Unnerving Occurrences in London?" he read the title page with difficulty, owing to the old-fashioned lettering. "Don't tell me someone other than me has been writing about your experiments?" John joked, grinning as Sherlock rolled his eyes.

"If you've quite finished being juvenile John, maybe you could make yourself useful?"

Shrugging off the insult John selected a lesser book from another shelf and sat at the table to read.

The two friends, conscious of the passing time, read through a dozen books each before Sherlock finally gave a shout of success.

"John, look at this!" he cried excitedly. "This even has its basis in Science John; I think we may have found our answer!"