The fog descends gently. White mist caresses the hard black tar of the road. It's twilight and the moon's just coming up in the distance. In the quiet evening, I can hear my boots crunching the gravel as I walk on the deserted stretch from my hotel to the shops, rubbing my fast-numbing hands.

I'm struck by the mystery that is Shimla - its haunting beauty, hills filled with echoes of lifetimes past, towering trees and foggy pathways carpeted by pine needles. They've been here for decades, long before I was even born.

I wonder if they've witnessed firsthand the strange legends I've heard during my stay here. Tales of those who've never really left Shimla, even though they've abandoned their physical form, whose spirits continue to inhabit beautiful old structures with new people living in them.

Heart-wrenching stories of loss, of unrequited love, of phantom memsahibs riding sidesaddle on ghost horses. Spine-chilling stories of hatred and evil, of possession and madness, and more.

From Ruskin Bond to Rudyard Kipling to Khushwant Singh, Indian literature is replete with Shimla's ghost stories. As my imagination runs riot, it's a relief to turn the corner into the diverting hustle-bustle of the market place.

I've never seen a ghost or had an encounter with the supernatural. As a rationalist I'm able to explain mysterious noises, disappearances, and dreams.

Travelling around the country, shooting for Raaz-The Mystery Continues, however, I've met many people who've had first-hand encounters with the supernatural. Their unshakable conviction in the narration of these experiences sends a chill down my rational spine.

In Surat, we heard of a village, which despite having a well in it, has been abandoned because of regular sightings of a ghost. Everyone in the village we met corroborated the authenticity of this tale. In Delhi, I met a medium who channels spirits.

This person was able to reveal facts I thought would be difficult to find out from public sources. We shot with special permission in an area in Bangarh in Rajasthan where the government does not allow access after 4 pm because of a history of untoward experiences.

If supernatural forces do exist, this place would be a favourite hangout. Ever so often, a crew member would come shaking with fear at something he thought he saw or heard, which we'd laugh away over a cup of tea and a pat on the back, but then were surreptitiously glad to call it a night.

In Mumbai, Mukesh Mills, a popular spot for film shoots has tales of a murdered dancer haunting it. Crew will testify to the number of unexplained technical glitches that occurred at the location from lights bursting into flames to hard disks crashing to unexplained soot on people's faces.

There are rational explanations for these experiences of course. It could be a stage-managed affair by a builder interested in propagating the story to gain access to the property.

It could be long-established associations of dark, abandoned places and whistling winds replaying images from the corners of the mind of what is considered spooky, attributing visions where there are none.

It could be a wish to thrill, like craving the excitement of being on a roller coaster, or a desire born of a yearning to believe in the possibility of a reconnection with a loved one who's passed away.

In a country besieged by superstition and belief in the supernatural, it's not hard to come across people in the most normal settings attributing events to otherworldly causes.

But then you come across incidents that you just can't brush away with rational explanations because you know the people who tell you about those are not given to exaggerations and cheap bluffs.

Like a friend's four-year-old daughter who has recurring dreams of herself as a man trapped in a burning tower screaming for help.

Her hypnotherapist says these could be past life visions, a concept her 'rational' parents struggle with but are increasingly prone to believe in the light of their daughter's descriptions.

If one can even consider the possibility of a past life, why not the fact that a soul may not have moved on after death?

Another friend's mother moved into an old building 30 years ago. Alone in the house, she would hear the sound of boots clicking through the long corridor outside the rooms.

Someone told her an Army general had died in the flat a few years ago. While spring-cleaning she found a pair of army boots. She put them into the ocean with a prayer for the general's soul to attain peace. She has never heard the sound of boots again.

These are real stories uncovered by my interactions and conversations with real people.

For most scientists and students of the subject like me, there's a sort of a cosmic battle raging between scientific reason and religious superstition, where only one can win. However, there are also a number of highly respected scientists who make the case that there is only so much that science can explain. After that, it's all hypotheses.

I read an article where Sir Peter Medawar, who won the Nobel Prize for medicine for his work on immunobiology, reflected on how science, despite being "the most successful enterprise human beings have ever engaged upon", had limits to its scope.

"Science is superb", it said, "when it comes to showing that the chemical formula for water is H2O. Or, more significantly, that DNA has a double helix. But what of that greater question: what's life all about?"

This, and others like it, Medawar insisted, were "questions that science cannot answer, and that no conceivable advance of science would empower it to answer".

They could not be dismissed as "non-questions or pseudo questions such as only simpletons ask and only charlatans profess to be able to answer. This is not to criticize science, but simply to calibrate its capacities."

While I've been a complete rationalist so far, and view with great skepticism tales of the after-life, I have to say that after meeting so many people with real stories in these last few months, I do listen to them with greater openness than ever before.