'And who undressed him again, typed out that suicide note, washed the lipstick from his face?'

'I think I know, but I shan't tell you. That's really what you employed me to discover, isn't it? That's what you couldn't bear not to know. But you killed Mark. You even prepared an alibi just in case it was needed. You got Lunn to ring you at college and announce himself as your son. He was the one person you could rely on absolutely. I don't suppose you told him the truth. He was only your lab assistant. He didn't require explanations, he did what you told him. And even if he did guess the truth, he was safe, wasn't he? You prepared an alibi which you dared not use, because you didn't know when Mark's body was first discovered. If someone had found him and faked that suicide, before you had claimed to have spoken to him on the telephone, your alibi would have been broken, and a broken alibi is damning. So you made a chance to talk to Benskin and put matters right. You told him the truth; that it was Lunn who had rung you. You could rely on Lunn to back up your story. But it wouldn't really matter, would it, even if he did talk? No one would believe him.'

'No, any more than they will believe you. You've been determined to earn your fee, Miss Gray. Your explanation is ingenious; there is even a certain plausibility about some of the details. But you know, and I know, that no police officer in the world would take it seriously. It's unfortunate for you that you couldn't question Lunn. But Lunn, as I said, is dead. He burnt to death in a road accident.'

'I know, I saw. He tried to kill me tonight. Did you know that? And earlier, he tried to scare me into dropping the case. Was that because he had begun to suspect the truth?'

'If he did try to kill you, he exceeded his instructions. I merely asked him to keep an eye on you. I had contracted for your sole and whole-time services, if you remember, I wanted to be sure I was getting value. I am getting value of a kind. But you mustn't indulge your imagination outside this room. Neither the police nor the courts are sympathetic to slander nor to hysterical nonsense. And what proof have you? None. My wife was cremated. There is nothing alive or dead on this earth to prove that Mark was not her son.'

Cordelia said:

'You visited Dr Gladwin to satisfy yourself that he was too senile to give evidence against you. You needn't have worried. He never did suspect, did he? You chose him as your wife's doctor because he was old and incompetent. But I have one small piece of evidence. Lunn was bringing it to you.'

'Then you should have looked after it better. Nothing of Lunn except his bones has survived that crash.'

'There are still the female clothes, the black pants and the bra. Someone might remember who bought them, particularly if that person was a man.'

'Men do buy underclothes for their women. But if I were planning such a murder, I don't think buying the accessories would worry me. Would any harassed shop girl at the cash desk of a popular multiple store remember a particular purchase, a purchase paid for with cash, one of a number of innocuous items, all presented together at the busiest time of the day? The man might even have worn a simple disguise. I doubt whether she would even notice his face. Would you really expect her to remember, weeks afterwards, to identify one of thousands of customers and identify him with sufficient certainty to satisfy a jury? And if she did, what would it prove unless you have the clothes in question? Be sure of one thing, Miss Gray, if I needed to kill I should do it efficiently. I should not be found out. If the police ever learn how my son was found, as they well may do since, apparently, someone other than yourself knows it, they will only believe with greater certainty that he killed himself. Mark's death was necessary and, unlike most deaths, it served a purpose. Human beings have an irresistible urge towards self-sacrifice. They die for any reason or none at all, for meaningless abstractions like patriotism, justice, peace; for other men's ideals, for other men's power, for a few feet of earth. You, no doubt, would give your life to save a child or if you were convinced that the sacrifice would find a cure for cancer.'

'I might. I like to think that I would. But I should want the decision to be mine, not yours.'

'Of course. That would provide you with the necessary emotional satisfaction. But it wouldn't alter the fact of your dying nor the result of your death. And don't say that what I'm doing here isn't worth one single human life. Spare me that hypocrisy. You don't know and you're incapable of understanding the value of what I'm doing here. What difference will Mark's death make to you? You'd never heard of him until you came to Garforth House.'

Cordelia said:

'It will make a difference to Gary Webber.'

'Am I expected to lose everything I've worked for here because Gary Webber wants someone to play squash or discuss history with?'

Suddenly he looked Cordelia full in the face. He said sharply: 'What is the matter? Are you ill?'

'No I'm not ill. I knew that I must be right. I knew that what I had reasoned was true. But I can't believe it. I can't believe that a human being could be so evil.'

'If you are capable of imagining it, then I'm capable of doing it. Haven't you yet discovered that about human beings, Miss Gray? It's the key to what you would call the wickedness of man.'

Suddenly Cordelia could no longer bear this cynical antiphony. She cried out in passionate protest.

'But what is the use of making the world more beautiful if the people who live in it can't love one another?'

She had stung him at last into anger.

'Love! The most overused word in the language. Has it any meaning except the particular connotation which you choose, to give it? What do you mean by love? That human beings must learn to live together with a decent concern for each other's welfare? The law enforces that. The greatest good of the greatest number. Beside that fundamental declaration of common sense all other philosophies are metaphysical abstractions. Or do you define love in the Christian sense, caritas? Read history, Miss Gray. See to what horrors, to what violence, hatred and repression the religion of love has led mankind. But perhaps you prefer a more feminine, more individual definition; love as a passionate commitment to another's personality. Intense personal commitment always ends in jealousy and enslavement. Love is more destructive than hate. If you must dedicate your life to something, dedicate it to an idea.'

'I mean love, as a parent loves a child.'

'The worse for them both, perhaps. But if he doesn't love, there is no power on earth which can stimulate or compel him to. And where there is no love, there can be none of the obligations of love.'

'You could have let him live! The money wasn't important to him. He would have understood your needs and kept silent.'

'Would he? How could he – or I – have explained his rejection of a great fortune in four years' time? People at the mercy of what they call their conscience are never safe. My son was a self-righteous prig. How could I put myself and my work in his hands?'

'You are in mine, Sir Ronald.'

'You are mistaken. I am in no one's hand. Unfortunately for you that tape recorder is not working. We have no witnesses. You will repeat nothing that has been said in this room to anyone outside. If you do I shall have to ruin you. I shall make you unemployable, Miss Gray. And first of all I shall bankrupt that pathetic business of yours. From what Miss Learning told me it shouldn't be difficult. Slander can be a highly expensive indulgence. Remember that if you are ever tempted to talk. Remember this too. You will harm yourself; you will harm Mark's memory; you will not harm me.'