Hobbes stepped away from the vehicle as the ambulance crew took over. This was his first week as a DC and it wasn’t what he’d expected, to be out on the street still, helping people like this. And then a voice had called to him from the murk of an alleyway. He turned and took a few cautious steps forward, until the woman’s face emerged as though from behind a curtain. Her cheeks and brow were spattered with droplets of red, and when she held up her hands, he could see they also were stained with blood. How stark and terrible it looked, amid the sulphurous air. She was in shock, her eyes wide open, her arms and upper body trembling.

The smog closed around them both.

Hobbes held her by the arm and tried to get her to make sense, but her words were garbled, almost mute. His own eyes were smarting and his throat was clogged. They were alone on an island, himself and this woman. Everyone else had faded away, even the ambulance and the two crashed cars. And then he felt a slight tug on his sleeve and he knew she was offering direction. Without thinking, he let himself be led further into the narrow alleyway, stumbling forward, his one free hand reaching out to scrape along the brick wall. Keep contact. Don’t get lost. But Soho was riddled with these dark, twisting back-streets, and he was new in the district, unsure of his way. It was bad enough in clear daylight, but in these conditions it was impossible. They turned a corner, the woman stopped, and he almost bumped into her. Now he saw the fear in her eyes. She was the same age as him more or less, mid-twenties, but the day’s events – whatever she had seen or found – gave her a sinister aspect, like something terrible drawn from a dream. For a moment she looked empty of all expression or feeling.

The alleyway was suddenly quiet. All of London had vanished down to this moment, her hand still in his, held tight against the coming danger, whatever it might be. Only her ragged breaths were audible.

‘What is it?’ he asked. ‘What’s happened to you?’

She made no answer.

‘Show me. Are we near?’

‘I’m scared,’ she replied, her first words.

Hobbes looked round helplessly. He was scared himself, but couldn’t dare admit it. Last week I was in uniform. That was protection. But now … His outstretched hand disappeared into the haze of yellowish-grey fog. He could see only the woman’s face, as it moved from side to side, her hair long and draggled over her eyes, the strands discoloured from a weekend’s exposure. He tried to smile, to look in charge. ‘It’s all right,’ he said. ‘Let’s retrace our steps – we can find the road again.’

‘No. No, you have to help me!’

She was suddenly focused. And, without a word, she set off once more, further down the alleyway, her form soon merging with the smog. Hobbes followed, taking one corner after another. This might as well have been the Victorian era: the same phantoms, the same demons prowled the streets.