heard a distant shout from Marianne. âDonât let him get away!â
He clambered down to the bottom of the ladder and stepped down on to the riverbed. The ground underneath his feet was muddy and treacherous, and at every footstep mud grasped at his legs, as if hoping to suck him down under the surface. Lifting his knees up as high as he could, Jonathan staggered away from the ladder and along the side of the wall. It was like trying to run through glue.
He looked up and saw Humble moving swiftly down the ladder after him. There was no telling what the giant might do if he caught him down here. Everything was black: the horizon dominated by the vast silhouettes of the bridge columns. There was no escape, no hiding place. Jonathan tried to move more quickly, but the mud was pulling him back, and he could feel his legs beginning to tire. Humble dropped lightly on to the riverbed and began to take purposeful strides in his direction. The mud was slowing him down too, but not by much.
The sound of traffic rumbling on the bridge overhead filled Jonathanâs ears. Glancing around for an escape route, Jonathan saw that the low tide had revealed a small inlet pipe feeding into the Thames. A battered grille had fallen away from the entrance, and a stream of brown water trickled forlornly out of it. A couple of stones had collapsed, blocking off part of the opening, but there was just enough room for him to squeeze through. It was hard to believe that a secret world lay beyond this grimy maw.
Humble was only a couple of squelching footsteps behind him. Jonathan forced one last effort from his legs and waded over to the pipe. He tossed his rucksack into the blackness and heard the splosh as it landed inside. Getting a handhold on the inside of the pipe, he lifted himself up and through the entrance. The mud released his feet with a defiant sucking sound. Jonathanâs body was now pressing down on his arms, and he had to wriggle like an eel to make any progress. The pipe sloped sharply upwards, and it took the last reserves of strengths in his body to scrape along it. The atmosphere was suffocating: there was hardly enough room to breathe, let alone to move. To make matters worse, scummy water soaked his face and seeped into his mouth.
A scrabbling noise came from near his feet. Twisting round, Jonathan could make out Humbleâs long arm slipping down the pipe after him like a python. There wasnât enough space for the giant to crawl after him, but he could still drag him out of the pipe. Jonathan cried out and forced himself deeper into the pipe, cutting his knee on a sharp edge in its concrete wall. His rucksack was blocking the way, and he had to frantically shove it forward with his head.
The hand was almost upon him. Jonathan felt a fingertip brush his trainer, and then suddenly the rucksack popped out of the other end of the pipe, and with one final thrust he followed it. Jonathan hit the ground with a thump and lay still, his breath coming in hoarse gasps. He had made it.
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Jonathan had come out in an underground circular chamber. Large grey pipes jutted out from the walls, and spat streams of water in the dank pool at the heart of the room. A wide run-off channel then carried the water out of the chamber and away into the blackness. The roaring of the cascades hurt Jonathanâs ears, and there was a stale smell in the air that stuck to his damp clothing. A ladder hung down from a small grille in the ceiling. Through the grilleâs thin bars a London street light threw down a glowing orange lifeline. It provided the only light in the room.
Moving his limbs stiffly, Jonathan checked his possessions. Amazingly, despite his desperate scrabble through the pipe, his rucksack hadnât been too badly damaged, although his clothes were wet through. And he could still feel the knife in his pocket. But his mobile phone wouldnât turn on and, even worse, the ink had run on the piece of paper