White-faced and wandless, Lockhart approached the opening. 'Boys,' he said, his voice feeble, 'boys, what good will it do?' Harry jabbed him in the back with his wand. Lockhart slid his legs into the pipe.

'I really don't think –' he started to say, but Ron gave him a push, and he slid out of sight. 

'Oh man, I wanted to do that,' huffed Amelia.

Harry followed quickly. He lowered himself slowly into the pipe, then let go.

It was like rushing down an endless, slimy, dark slide. He could see more pipes branching off in all directions, but none as large as theirs, which twisted and turned, sloping steeply downwards, and he knew that he was falling deeper below the school than even the dungeons. Behind him he could hear Ron, thudding slightly at the curves, and a small scream that belonged to Amelia.

And then, just as he had begun to worry about what would happen when he hit the ground, the pipe levelled out, and he shot out of the end with a wet thud, landing on the damp floor of a dark stone tunnel, large enough to stand in. Lockhart was getting to his feet a little way away, covered in slime and white as a ghost. Harry stood aside as Ron came whizzing out of the pipe, too. Amelia shot out after.

'We must be miles under the school,' said Harry, his voice echoing in the black tunnel.

'Under the lake, probably,' said Ron, squinting around at the dark, slimy walls.

'Yuck,' muttered Amelia. She took her wand out and waved it around drying their clothes. 'That sticky wet feeling was going to drive me crazy,'

'Short drive,' said Ron.

'Touché,'

All four of them turned to stare into the darkness ahead.

'Lumos!' Harry muttered to his wand and it lit again. 'C'mon,' he said to Ron, Lockhart, and Amelia, and off they went, their footsteps slapping loudly on the wet floor.

The tunnel was so dark that they could only see a little distance ahead. Their shadows on the wet walls looked monstrous in the wandlight.

'Remember,' Harry said quietly, as they walked cautiously forward, 'any sign of movement, close your eyes straight away ...'

But the tunnel was quiet as the grave, and the first unexpected sound they heard was a loud crunch as Ron stepped on what turned out to be a rat's skull. Harry lowered his wand to look at the floor and saw that it was littered with small animal bones. Trying very hard not to imagine what Ginny might look like if they found her, Harry led the way forward, round a dark bend in the tunnel.

'Harry, there's something up there ...' said Ron hoarsely