"Now move forward to 2202, my fortieth birthday. I jump back from that far end of the line to 1840 and I kill the Original Oxford before then jumping to the start of the line, where we are now."

"The present moment," offered the marquess.

"Yes. Now, at 1840, the line has been cut. The stretch of it containing all the Original Oxford descendants is no longer joined to the part of the line that we are on. It still exists, perhaps, but not for us. For us, everything after the death of the Original Oxford must be written anew. There's nothing there for me to jump forward into!"

"But you went to 1877. That's beyond the cut!"

"Yes, it is, and I've been puzzling over that all night. I think I know what happened. I think I jumped to the end of my natural life span."

"I don't understand you."

"Henry, if I remain in this time, by 1877 I will be eighty years old. Friday March 9, 1877, I am certain, will be, barring accidents, the end of my days."

"Do you mean to suggest that you can travel within your own allotted time, as it were, but to go beyond that you need a future which, for you, has already been established?"

"Yes, exactly."

"To all intents and purposes, then, you seem to have wiped yourself out of existence. But why, Edward? Why did you kill this man?"

"I'd rather not go into that. Like I said, it was an accident."

"So go and prevent it. If you can travel as far as 1877, then 1840 remains well within reach. Go and stop the death of the Original Oxford."

"Henry, don't you see? I'm here; I killed him; no one stopped me; therefore if I try, I will surely fail!"

"The complexities of time travel are far beyond me," answered Beresford, "but in the future you were alive and invented a time suit. That cannot have been possible if someone killed your ancestor. Yet here you are. It seems to me that just because you perceive that things occurred a certain way doesn't mean you can't go back and alter them."

Edward gazed into s.p.a.ce.

"Yes," he whispered thoughtfully. "Yes, I suppose that's true. It's worth a try!"

He sprang to his feet.

"I have to work on the suit, Henry. There's damage to the helmet and the control unit requires further attention!"

"For pity's sake, man, rest first! You look as if you've not slept all night!"

"I haven't! There's no time for sleep!" barked Oxford, crossing to the table where his gear was laid out.

Beresford shook his head.

"Of all people," he said quietly, "I would have thought you'd have all the time in the world."

Three years later, Edward Oxford hit the ground running.

He was farther away from the other two Oxfords than he'd planned and, as he raced past a policeman, he realised that he was too late, as well; the two men were already locked together; the pistol was already raised toward the queen.

"Stop, Edward!" he bellowed.

Suddenly a bolt of energy flashed out of the control unit and into the ground. He doubled over in pain as the charge ripped through him and looked up again just as the pistol went off and Queen Victoria's head sprayed blood.

The monarch fell backward out of her carriage.

The Oxfords wrestled. The Original tripped and went down, his head smacking onto the railings.

It was me, thought the time traveller. The distraction; the shout and the flash. I looked up at myself here on the hill and in doing so moved my ancestor's arm. I caused the pistol to point at her head!

"No!" he groaned. "No!"

The control unit let loose a shower of sparks.

He turned.

The policeman had almost caught up with him.

Oxford sprang over the constable's head and landed back in 1837.

"I can't stop it!" he told Henry de La Poer Beresford as he entered through the veranda doors. "It might not have happened at all if I hadn't gone back just now!"

He dropped his face into his hands and moaned.

"Sleep," ordered Beresford. "Once you are rested, you'll think more clearly. We'll find a solution. And remember, you have forty years in which to work on it."

"b.l.o.o.d.y h.e.l.l!" cursed Oxford. "I can't stay a Victorian recluse for the rest of my life. Besides, my wife is expecting me home for supper."

He suddenly chuckled at the contrast-the extraordinary and the mundane-and lost control of himself, throwing his head back and laughing wildly, a harsh and unbalanced noise which caused the marquess to step back a pace.

It echoed through Darkening Towers, that horrible laughter.

Maybe it echoed through time.

DISSUASION.

Nothing is permanent, least of all the thing you think of as I.

-HENRY DE LA POER BERESFORD, 3RD MARQUESS OF WATERFORD.

-dward Oxford raved all evening until Beresford summoned Brock and together they half pushed, half carried him up the stairs and into his bedroom. They pulled off his clothes-both had learned how to unfasten the time suit-and put him to bed. He eventually fell into a fitful sleep, muttering to himself, groaning, tossing and turning.

When he shuffled into the morning room the next day, he looked gaunt and fevered, with dark circles around his eyes.

"Eat," commanded Beresford, indicating the food the butler had placed on the table.

Oxford sat and ate in a desultory manner, his eyes glazed.

"I have a question," said the marquess.

His guest grunted.

"Where is your ancestor now, at this moment, June 1837?"

"He's fifteen years old. He lives with his mother and sister in lodgings at West Place, West Square, Lambeth."

"And where will he be when you kill him?"

"Green Park."

"Then you must go to Lambeth, find him, and convince him that he'll be murdered if he visits Green Park in 1840."

Oxford leaned back in his seat and looked at the marquess.

"Yes," he mumbled. "Yes. If I can manage it; if I can bear the exposure and hold myself together, it could work."

"Do you know where West Place is?"

"Yes, it's right beside the Imperial War Museum."

"The what?"

"The Imp-No, wait, that hasn't been built. It's-It's the Bethlem Royal Hospital!"

"Bedlam, you mean?"

"The very place where my ancestor will spend twenty-four years of his life if I prevent myself from killing him."

"He was-is, I mean-a lunatic, then?"

"At this point in time, 1837, he's beginning to show symptoms of mental disturbance. The illness reaches its peak in 1840, when he commits a criminal act. He's caught, tried, and committed to Bedlam. Over the next couple of decades or so, he recovers his wits, though he remains incarcerated. They eventually move him to Broadmoor, then he's freed and deported to Australia where he meets and marries a girl. They have a child who is my Idon't-know-how-many-times-great-grandfather. "

Beresford leaned forward and rested his chin upon his hand, contemplating his strange houseguest.

"But now," he muttered, "none of this will happen?"

"I came back in time to prevent his crime," answered Oxford, "but instead killed him."

"So no happy ending in Australia, then."

"He didn't have a happy ending anyway, Henry. Look at this."

Oxford pulled a wallet from his pocket and took a folded sheet of paper from it. He slid it across to Beresford. The marquess unfolded it and saw that it was a letter, though written in no type of ink that he'd ever seen before. He read it: Brisbane, 12th November, 1888 My DarlingThere was never any other but you, and that I treated you badly has pained me more even than the treasonable act I committed back in '40. 1 desired nought but to give you and the little one a good home and that I failed and that I was a drinker and a thief instead of the good husband I intended, this I shall regret to the end of my days, which I feel is a time not far off, as I am sickly in body as well as in heart.I do not blame you for what you do now. You are young and can make a good life for yourself and our child back in England with your parents and I would have brought more misery upon you had you stayed here, for I have been driven by the devil since he chose me as his own when I was a mere lad. I beg of you to believe that it is his evil influence that brought misery to our family and the true soul of me never wished you anything but happiness and contentment.You remember, my wife, that I said the mark upon your breast was a sign to me of G.o.d's forgiveness for my treachery and that in you he was rewarding me for the work I had done in hospital to restore my wits and good judgment?I pray now that he looks mercifully upon my failure and I ask him that the mark, which so resembles a rainbow in its shape, and which lays also upon our little son's breast, should adorn even y of my descendants forevermore as a sign that the great wrong I committed shall call His vengeance upon no Oxford but myself, for I it was who pulled the triggers and no other. With my death, which as I say will soon be upon me, the affair shall end and the evil attached to my name shall be wiped away.You have ever been the finest thing in my life.Be happy and remember only our earliest days.

Your loving husband Edward Oxford P.S. Remember me to your grandparents who were so kind to me when I was a lad and who, being among the first f I ever had, I recall with immense fondness.

"It's a scan of the letter he sent to his wife after she left him and returned to her parents in England. I have the original at home. It has been pa.s.sed down from generation to generation," revealed Oxford.

"Fascinating! A letter from the future!" exclaimed Beresford.

"For me, from the distant past," countered the other man. "And now, a letter that will never be written."

"Yet here it is in my hand," muttered Beresford, wonderingly. "It raises some questions, my friend. For a start, who was the wife?"

"I don't know. There's no record of her name. All I know is that she was the daughter of a family he was acquainted with in the days before he committed his crime. You'll note his postscript."

"Yes. So it was a crime of treason, was it? It must have been bad, else you wouldn't have travelled through time to prevent it."

"It was. It has been an embarra.s.sment to my family for generations."

"But you're not going to tell me what it was-or should I say, will be?"

"No, I'd rather not."

"What of this rainbow he mentions?"

"A small birthmark above the heart, bluish and yellow in colour and shaped like an arc. It has appeared sporadically on Oxfords throughout the generations. I don't have it but my mother does."

"A mark of G.o.d's forgiveness, or so the poor fellow thought," murmured Beresford. "What ultimately happened to him in your history?"

"He died a pauper in 1900."

"So if you find him at the present time and dissuade him from ever contemplating the crime, you might save him from his miserable fate-but surely this presents a problem: for if he doesn't commit the crime then he won't be sent to Australia, won't meet the girl, and your ancestors won't be born."

Oxford nodded and wearily ran his fingers through his hair.

"I thought of that before I began this venture," he admitted. "But consider this: the Original was acquainted with the girl's grandparents before he was incarcerated. There is, therefore, every chance that if he remains at liberty he will meet and woo her before she emigrates, and that she will marry him."

Beresford looked astonished. "Good gracious, Edward-do you mean to tell me that you embarked on this scheme with only that vague possibility to protect your future existence? Are you out of your mind, man?"

"Shut the h.e.l.l up!" snarled the time traveller, his eyes suddenly afire. "It's a matter of probability, and probability theory is a science of the future, so you are hardly qualified to comment, are you? You d.a.m.ned primitive ape!"

Beresford shot to his feet and glared at his guest. "How dare you, sir! I'll remind you that this is my home," he snapped, "and I'll not be spoken to in that manner! I'm going to tend to the horses. I suggest you consider your position here very carefully, Mr. Oxford, because I'll be d.a.m.ned if I'll shelter any man who addresses me so!"

He stamped out of the room and slammed the door behind him.

Edward Oxford stared after him, then stood, moved over to the fire, and watched the flames consuming the logs.

He landed in the grounds of Bedlam by the southeastern wall at eleven o'clock that same night, a mere two hours into the future; it was still late June 1837. The big hospital loomed behind him, wreathed in fog.

Vaulting over the wall, he dropped into a cemetery, which he crossed rapidly, then jumped the railings on the opposite side, hitting the cobbles of the street beyond directly in the path of a businessman, who screamed, dropped a sheaf of papers, and ran off.

Oxford looked to his left, to where the road joined a busy thoroughfare.

"That must be St. George's Road," he muttered. "This is Geraldine Street, so West Place is straight ahead."

He heard footsteps approaching and quickly walked away from them, crossing the road and entering a mist-heavy square enclosing a small fencedin public garden in the middle. Beyond the railings, trees sagged over deep wells of darkness. It was the perfect hiding place.