It hit him on the shoulder like a hammer hurled from hell. His legs were still running as fast as they could so the blow knocked him off balance and he stumbled down the grassy slope and into the icy water of the lake. The mud grasped his ankles like bony hands and pulled. He struggled briefly and tried to scream but the mud and the water were in his mouth. A few frantic bubbles then nothing. Minutes later the nightbirds were gliding gracefully across the lapping water.

He had often joked about being the only jogger not being chased around the park. He went at his own speed but everyone else, the serious ones, the ones who sped past him up the hill, they were being chased by something large and terrifying and invisible. That was why they went so fast, they did not dare slow down. Then, as he ran and the nights grew longer, grew towards his running time, he thought more about the story and as people passed he squinted after them, trying to make out their demons.

Then one evening, just for a flash, he saw one. As the path came out from the trees, the man in shorts ran past him, face contorted, and John caught a glimpse of the animal chasing him. Wolf-like, foam dripping from its jaws, eyes coal red in the dark, it ran snapping at his heels, never quite touching but close enough that he could feel its cold breath on his legs.

And then it was gone. John shook his head. He was sure he had seen it but it was gone. He walked the rest of the way home.

The next few times he went for a run he looked carefully as people passed him. Nothing was chasing them that he could see but still they ran faster. He felt odd, uneasy, when he ran now.

He thought twice about running on Halloween but then put on his kit. It was only just dark and there would be people about, trick or treating. His front door creaked as he closed it and his footsteps seemed to echo on the stairs. As he had imagined, clouds scudded across a deep black sky.

He jogged slowly down the road. There was nobody about. Strange. The castle on the hill hung in its own red light. He crossed the road and squeezed through the gap in the hedge into the park. The trees whispered.

He turned down the hill under the trees. It was darker today and the knobbly roots were hidden. He tried to slow down, tripped and fell. As he pushed himself up onto his knees something touched his hair. Heart pounding he jumped to his feet and looked around and there it was. He had never seen it before but he knew what it was, his blood felt what it was and froze. Down the hill again he half staggered half ran then at the bottom, lungs bursting, he ran and ran and ran until he could not run any more but run he did. He looked around. It hit him on the shoulder like a hammer hurled from hell.