He pulled up outside a guard box and she got out, after paying him.

‘Would you wait for me? I need to get back to the station in about an hour or so?’

‘Of course, love. If you’re paying, I’ll wait.’

‘Run the meter.’

She nodded at the guard, who found her on his list, checked her ID and let her through. The walk up to the main reception was long and lonely. She wished Demi was beside her, or Johnny. Two voices of reason who she’d trust beyond all others.

Or Ted. She hadn’t had the heart to ask him, and pull him away from his afternoon with Josie. Because he’d have said yes.

A man in a suit was waiting for her and walked towards her with an outstretched hand. It was the guy she’d been talking to on the phone about The Teacher. She’d expected him to be reticent, or nervous about the pending meeting, but, in fact he was just as excited about meeting somebody who’d been apprehended by his patient, and survived. He jabbered on, and she barely registered what he said. Her nerves jangled and she tried to breathe. She imagined her letters being penned behind these walls, by The Teacher’s hand, and sent to be stamped in an office somewhere. Her stomach turned upside down.

Then they were inside a set of metal doors, each locking in front and behind as they passed through.

‘May I go in alone?’

‘Of course. I expected you to say that. I’ll be watching on the screen.’

‘I know. I hope I get something for your research.’

‘Here we are. We’ve finally found the leak in our system, have you been informed?’

‘No.’ Kelly was puzzled.

‘The letters, sent to you I believe?’

‘What about them? I just know they were posted in Surrey.’

‘They were traced to one post box, near the house of an employee of ours. She has admitted taking financial reward for posting the letters on behalf of our patient. She is being suitably disciplined.’

‘That makes sense. Thank you for letting me know.’

Kelly looked along the corridor. It was the isolation unit, where patients were kept alone for their own safety. It was painted white, with a green linoleum floor, and smelled of disinfectant. There wasn’t much noise, apart from the odd clang of a trolley or a door elsewhere. A series of doors lined the walls and at the end there was a room, and she saw that Amy Richmond was waiting for her, behind a strengthened screen, sat in a chair, staring at the ceiling. The hairs on Kelly’s neck stood up. She turned to the doctor and he told her to wait for the guard to unlock the door, then go through the inner door and sit down in front of the patient.

‘Did you agree with the verdict?’ she asked.

‘Insanity? Of course.’