“Everyone is born with a license,” says our Hmong guide, Chuaher, as we toil up the steepening slopes out beyond the central Laotian village of Long Lao. “And on that license,” he pauses for breath, “everyone has an expiry date.”

In the heavy mist of this Mekong mountain morning, our party of five has already trekked past stands of thin rubber trees and skirted fields of bright green sacha inchi-nut bushes. Then, after passing a last, solitary bamboo lean-to, the jungle spreads out its protean shadow ahead of us, up beyond the shiny green leaves and twisting vines of the raggedy forest edge.

“Only the shaman can know what date is written on those licenses,” Chuaher continues, as we move into the gloom of vegetation, the path behind us quickly vanishing. “Only they can journey beyond to the Otherworld and ask the spirits how many years a person has left.”

In the shadowy depths of these ancient, jungled hills, 50 miles south of Luang Prabang, there seem to be plenty of ways that expiry date might be brought forward, too.

First of all, there are the dab qus – the wild spirits of the forest – whose feelings towards humans can be decidedly malignant. Most dangerous of these is the Mos Hlub, a fantastical, bigfoot-style, flesh-eating giant, that bounds about the jungle “like this,” Chuaher demonstrates, striking a pose a bit like a kangaroo. The Mos Hlub grabs you by the wrists and then looks up at the Moon; when he looks down, he eats you. “That’s why you must wear the bamboo amulets,” our guide warns, “so you can slip out of them while he is looking up, and run away.”

Yet, in your flight you still might fall foul of the Poj Ntxoog, a spirit that manifests in these dense forests in the form of a small girl with her feet on backwards. Then there is the Phim Nyuj Vais, a giant, psychotic monkey with the skill of disappearing in one place and then suddenly reappearing in another.

As we pause for a moment under a giant, old growth mango tree, Chuaher tells us how it is almost impossible to kill this beast. Yet, “He hates the smell of chilli,” our guide adds. “He doesn’t like it and runs away fast if he smells it!”

Suddenly, a giant birdwing butterfly flits through the deep shadows to our left, startling us with its white, skeletal markings. All around there is the deep smell of the forest floor – of monkey-ear mushrooms and wild sweet potatoes, strewn like cannonballs amongst the gullies of long dead streams.

“In any case,” starts up Chuaher, whose grandfather is a shaman, “that’s what we Hmong believe.”

Later though, it seems those beliefs may have caught on elsewhere, deep in the heart of this mystical jungle.

After lunching on the banks of a crystal-clear sacred spring, just north of the Kuangsi Falls, I notice something missing.

Where Chuaher had earlier left us a pile of small, plastic packets of chilli powder to pep up our noodles-wrapped in banana leaves, only one remains.

Hesitating at first, I then pick it up and surreptitiously sneak it into my pocket.

Just in case, you understand, just in case.