Somewhere in the middle of the remote Kalahari desert in South Africa, nestling among the dry ochre veld, is a small weed-covered pool at the bottom of a crater. Ordinary except for its stillness — the casual observer wouldn't pay it much attention, wouldn't give it a second thought. Unless they were to swim in it. Or dip a toe into it. Then they'd notice something wrong. Something different.

First they'd notice the water was cold. Freezing, in fact. The sort of cold that doesn't belong to this planet. The sort of cold that comes from centuries and centuries of silence, from the most ancient recesses of the universe. And, second, they'd notice that it was almost empty of life, only a few colourless canefish living in it. Last, if they were foolish enough to try to swim in it they'd discover its fatal secret: there are no sides to this pool and no bottom — just a straight, cold line to the heart of the earth. Maybe that's when it would come to them, repeated over and over again over in the whispered ancestral languages of the Kalahari people, This is the path to hell.

This is Bushman's Hole. This is Boesmansgat.

13 May

Just after lunch on a Tuesday in May and nine feet under water in Bristol's 'floating harbour', police diver Sergeant 'Flea' Marley closed her gloved fingers round a human hand. She was half taken off-guard to find it so easily and her legs kicked a bit, whirring up silt and engine oil from the bottom, tipping her bodyweight back and upping her buoyancy so she started to rise. She had to tilt down and wedge her left hand under the pontoon tanks, then dump a little air from her suit so she was stabilized enough to get to the bottom and take a little time to feel the object.

It was pitch dark down there, like having her face in mud, no point in trying to see what she was holding.