The stairs led them down and down into a warren of empty rooms crawling with mould and rotten with damp. On the ground floor they found an entrance hall flagged in worn stone, and the entrance to a cloister, and on the far side, the abbey chapel. Other church buildings had been taken over as prisons, but it was clear that this abbey was too far gone for that. In one room, the ceiling had burst like a fat raindrop, splattering lathe and plaster across the floor. A pigeon swooped through the hollow space and into the dark room above.

‘I thought the church was supposed to be rich,’ said Ada, toeing the dried husk of a dead bird.

‘That does not mean they spend their money wisely,’ replied Guil.

On entering the cloister, they found the first signs that the place was occupied. Stacks of empty crates were lined against one wall, straw trailing onto the cobbles. Smashed glass was mixed among it, still bright and gleaming. Ada picked up a large fragment, the remains of a wide-neck opening, and sniffed it.

‘I know what this is. It’s turpentine. It’s used for preserving specimens. Getting a skeleton is easy, you just boil the body until the flesh falls off. Preserving specimens is harder.’

‘Specimens?’ asked Guil.

‘Organs. Dissected animals. Deceased things. They use them in the surgical schools. It’s hard to get fresh corpses, so preserves have to do.’

‘And yet our dear duc seems to have a ready supply coming to him here,’ said Camille.

She tried the door of the chapel, which opened with a shockingly loud squeal.

A bird launched from its perch, an explosion of feathers and noise.

They froze. Anxious sparks danced between Olympe’s fingers.

But no one came.

Silence claimed the cloisters again, and Camille eased the door further open.

Inside, the milky daylight filtered through stained glass windows, casting a mottled pattern over the flagstones. Dim as it was, it was clear that the chapel had been given over to a darker purpose. The pews had been removed, replaced by two long wooden benches, and makeshift shelves of planks balanced over lumps of scrap masonry. Each was filled with jars, some murky, some bright, all with yellowy-grey objects suspended in clear liquid. By the benches was a trestle table covered in oilcloth and spread with knives and hacksaws and all manner of blades and slicing implements. The floor was dull, much sluiced but still sticky with something dark that caught in the grouting.

On each bench lay a human body. Adult, limp, splayed open by a thousand pins. Skin peeled back like the rind of an orange, bone, vein and muscle bared. On the woman to the left, both legs had been unzipped from ankle to groin, butterflied and still grisly fresh. The second was in a worse state. Smelling strongly, the man’s belly had been scooped out like a melon, intestines coiled over his ribs.