The A/V showed two suited figures, as seen from Dan’s point of view, kneeling at the bottom of a pit that looked about five metres deep, with a series of wide steps cut into the sides. The two men’s helmets almost touched as one pointed at hundreds of indentations drilled into the lower steps, and arranged in stylized, looping patterns. One turned to glance towards Dan, and Jeff saw Mitchell Stone’s face behind the visor.

The video blurred as Dan looked up suddenly at the shallow, copper-coloured dome of the chamber’s ceiling high overhead. Jeff noticed a fourth suited figure waiting up above, and Lucy’s face was visible through the visor: small and imp-like, loose wisps of her blonde hair pressing against the clear polycarbonate.

As Dan clambered up the wide steps, Jeff saw that half a dozen carbon arc lights had been mounted on tripods close to the chamber entrance. They cast incandescent light across dozens of pits, each one only narrowly separated from the next.

Dan then turned to look back down at the suited figures of Mitchell Stone and Erich Vogel, still crouching at the bottom of the pit. Without any warning, a viscous, oil-like substance began to gush out of the indentations, flooding the pit with astonishing speed. Jeff heard Lucy yell a strangled warning, and Stone and Vogel both jerked upright as if they’d been scalded. The liquid was already covering the top of their boots.

It was Rodriguez, all over again.

From the subsequent sudden blurring of the video, it was obvious that Dan had descended into the pit once more, in order to try and reach the two men. Stone and Vogel were already making their way towards the steps but, even as Jeff watched, he saw their movements become slower, as if the oil were congealing around them. By now it was up to their knees.

The oil appeared to defy gravity, racing up the sides of their suits and soon swallowing them both up in a black tide. Stone was the first to collapse, followed by Vogel a moment later. Jeff watched in mounting horror as their suits began to disintegrate, the metal and plastic dissolving and falling away from their bodies with astonishing speed. Jeff had one last glimpse of Stone’s eyes rolling up into the back of his head, before they were both swallowed up by the still-rising tide.

The oil had behaved purposefully, like something alive, which made Jeff think of childhood monsters, of yawning black shadows filled with imaginary horrors. Tears pricked his eyes but he couldn’t bring himself to stop watching.

The video jerked once more as Dan hurried back up and out of the pit, with understandable haste. Jeff saw Lucy step back, her face aghast, then, with a terrified cry, stumble backwards over the lip of an adjacent pit.