It is December 4, 1532, in the Alpine Town of Chamborey, in what is today southeastern France.

In the dead of night, a young blacksmith is woken by a frantic knocking at his door.

As he stumbles out of bed, rubbing his eyes, he recognises the stench of smoke in the air.

At the door is a breathless cleric. His sooty face is streaked with sweat and his cassock dusted with ash.

He explains that the chapel is on fire at the Chateau de Chambore, the seat of the Dukes

of Savoy.

And worse, the holy shroud said to be the burial cloth of Jesus Christ, is trapped, locked

behind an iron grill. They need his help. The blacksmith throws on a linen shirt and

britches, then after quickly gathering his tools and wrapping them in their leather roll, he

hurries after the cleric.

As the pair make their way through the narrow town streets, Chambore is in chaos with panicked cries.

They climb the hill to the chateau, which overlooks the town.

As they approach an arched gateway, guards holding gleaming halberds wave them urgently through,

and soon they're close enough to feel the heat.

Looking up, they see flames, licking at the high gabled roof and narrow Gothic windows of the pale, austere chapel. They slip through a side entrance, as timbers crack and shriek overhead.

Sweat, beads instantly on the blacksmith's brow as he follows his guide down a smoke-filled corridor.

Somewhere on the other side of the wall, a beam collapses with a booming crash.

Coughing and half-blinded by the smoke, they find their way to where the shroud is kept behind the high altar of the chapel.

There, the cannon and two Franciscan friars in brown habits crowd around a cavity in the wall.

Inside it, the precious silver casket is secured by an iron grill with four locks, each opened by separate keys.

But in this heat, the cleric explains, the locks have deformed and are failing to open.

Hence the holy men's desperation as they try to prize the grill off with makeshift tools.

...