Her younger, married sisters had turned up yesterday. They filled the house with sniffles and whispers and husbands. These were tall, silent presences, who made no comment but held their heads at sympathetic angles.

The question – why? – was brought out again and aired, like a wound from which the dressing was removed, while those present peered at it with a mixture of curiosity and distaste. Quinn knew from his own experience that it was a question that the living would never tire of asking, but to which no adequate answer could ever be found. Because the only one who had the answer was dead.

The fog of his temporary blindness lifted partially, enough to allow him to make out the dark rectangle of Dr Casaubon’s door. He perceived it as black, though whether that was its true colour, he could not remember. He pushed against the field of blackness, this time without ringing the bell first. It was within the hours of Dr Casaubon’s surgery, and the doctor was expecting him.

Now the self-imposed darkness was absorbed into the drapery-imposed darkness of Dr Casaubon’s surgery. The voice of that darkness had just asked him a question about his father’s suicide.

‘Once again, I did not come here to be psychoanalyzed by you.’ But the question of why he had come to Dr Casaubon was only vaguely answered in Quinn’s mind. He might justifiably say that it was to do with the investigation. But even he sensed that was a pretext rather than a reason. Was it possible that it was to do with Miss Dillard’s suicide? If so, it was strange that Quinn was scrupulous in avoiding any mention of what had happened at the lodging house.

‘And yet you have consented, once again, to lie down on my couch.’

‘I did not want to. I did it to please you.’

‘Are you often driven to do things to please others?’

‘Far from it. Those who know me would find that rather amusing.’

‘Do you feel the need to earn the approval of your father?’

‘How can I? He’s dead.’

‘But that need may still be there. Especially as he died unexpectedly, when you were a young man. What will happen is that you will transfer these feelings on to other men, older men, father figures, we might call them. That is why you lay down to please me. There is someone in your life whom you would describe as a father figure? Your superior at your work, for example?’

‘Sir Edward.’

‘You work hard to please him. You sometimes go too far, in fact. That is why people die. It is all because you are trying to please Sir Edward, and through him your father.’

‘But Sir Edward frequently disapproves of my methods, or so he says.’

‘The eternal tension between father and son is played out. You seek his approval, which he perpetually withholds.’

Quinn shook his head impatiently. An invisible gesture in the darkness. ‘I did not come here for this. Doctor, have you any experience in the psychology of murderers?’

‘I have had the privilege to speak to a number of murderers in my career.’

‘The privilege?’

‘Murder is an act of wish-fulfilment. Wish-fulfilment is the cornerstone of Freudian dream analysis. Anyone who has lived out an impulse of wish-fulfilment to such an extent is naturally of interest to a doctor of the mind.’

‘It is a strange word to use.’

‘Do you not find yourself drawn to murderers? Could that not be why you have chosen this unusual profession? Is it not a privilege for you to be able to hunt them down and kill them?’

‘I do not always kill them. That is certainly not my intention when I begin an investigation. Sometimes it is necessary to take steps to protect myself and the public. But I have not come here to justify myself to you.’

‘You have so far told me several reasons why you did not come here today. You have yet to tell me why you did.’

‘I have come to ask for your assistance in an investigation.’

‘My assistance?’

‘If you were to look at the work of a particular artist, would you be able to tell if that artist had a predisposition to murder?’

‘A lot would depend on the nature of the work. Are these paintings?’

‘Not paintings. Motion picture films. The subject is a film director.’

‘You have piqued my interest, Inspector. However, I cannot promise any definite results, and it might be rash in any event to offer firm pronouncements, especially if there is a danger you might act upon them.’

‘How do you mean?’

‘I wouldn’t want to be the reason you killed someone.’

‘I would not act solely on the basis of your opinion. I would only make an arrest if there were also material evidence against the suspect. And as I said before, it is not my intention to kill anyone.’

‘I confess, it is an intriguing proposal.’

‘My sergeant is waiting outside in a car. Would it be possible for you to accompany me to the Yard now? We have the films there. And a projector with which to view them.’

‘Very well. You have come at a good time. I have finished my appointments for the morning.’ Dr Casaubon began to draw back the drapes. ‘But tell me, Inspector, what is the name of this director? I am quite an aficionado of the kinema.’

‘Konrad Waechter.’

There was a beat. ‘Of course!’

‘By that, do you mean that you think it is possible, after all?’

‘Let us watch the films, Inspector. Then I will be able to offer a more informed opinion.’

A rectangle of light shimmered and fluctuated, as if trying to latch itself on to something solid in the darkness. Its edges sharpened and softened. Swirling flecks and particles swam across it, as it shrank and expanded, jerking itself into its ideal size.

Macadam positioned the projector to shine its beam on to the one vertical wall in the department, the wall that usually used held the photographs of victims, sketches of crime scenes, biographic details of suspects and other notes and documents relevant to the investigation. This was no ordinary wall, it was the wall.

That morning, Tuesday, after a day of prompting, Waechter’s back catalogue of films had finally arrived from Visionary Productions. It was at that point, when he realized that he had no real idea what he was looking for, that Quinn decided to involve Dr Casaubon of Harley Street.

And so they were now about to cast upon the wall the product of a man’s imagination. A man who had the power and the habit to give his dreams form and to make them move and dance across the dark.

They stared at the blank rectangle of light waiting for these dreams to form. As long as Quinn kept his focus on that luminescent area, he could keep whatever horrors the darkness contained at bay. The darkness held the memory of her trembling body, the constricted rasp in the back of her throat, her pupils dilated to the full.

‘So, do you fancy him for Dolores Novak, guv?’ asked Inchball.

Quinn felt a strange disconnectedness, almost a disembodiment. It felt like he was cast under a spell he was reluctant to break.

Macadam answered the question for him, as he made his final adjustments to the projecting lens. ‘You know there is nothing to place him at the scene of her murder, sir.’

‘Nuffin’ to say he was there. Nuffin’ to say he wasn’t,’ argued Inchball.

‘The only men we know were there were her husband, Porrick and Lord Dunwich,’ countered Macadam, laying the ground for a theory. He closed the shutter between the arc lamp and the projector, plunging them into near darkness. He worked the end of the film through and into place on the sprockets. It was an operation he had practised many times since the projector had arrived.

Quinn was generally content to let his sergeants argue it out. In the past their back and forth bickering had often led to new insights. But now he felt compelled to intervene, as much to prove to himself – as well as his men – that he was present in the semi-darkness. ‘And who of them has a motive?’ He felt his lips tremble in the aftermath of the question.