"In which case," Mr. Dunworthy was saying, "it would be impossible to trace the initial altering event back to its source."

"But from what you've said, you don't know that there was an altering event at all," Polly argued. "There's no proof you did anything."

"Yes, there is. Up till then there hadn't been any slippage. It began on the very next drop. Unfortunately, that was a drop to the Battle of Trafalgar, and the one after that was to Coventry, and we drew the erroneous conclusion that the slippage made it impossible to alter events."

"But you said you came through a day later than you were supposed to."

Mr. Dunworthy shook his head. "I'd made an error in the coordinates. I checked it as soon as I returned. The net was set for the seventeenth."

"What about locational slippage? You said you thought you'd gone through to Marble Arch."

"No, I said I might have. We couldn't do specific locations back in those days, only a general area."

"Then there might have been locational slippage."

"But if there had been, it would have prevented me from colliding with the Wren." He smiled bitterly at her. "No, I caused the slippage and then misinterpreted that cause. And we proceeded to wander through history," he said bitterly, "gawking at wars and disasters and cathedrals, with no thought of the consequences of what we were doing."

Polly looked at Mr. Dunworthy sitting there. Mr. Humphreys had said he looked like he had the weight of the world on his shoulders. And he does, she thought.

"For the past forty years, we've been blundering through the past like bulls through a china shop, fondly imagining that it was possible to do so without bringing about disaster, till it finally came crashing down on us. And on you."

"But there was no way you could have known," Polly said, reaching out to pat his arm.

He drew his arm back violently. "There were dozens of clues," he said furiously, "but I didn't want to see them. I wanted to go on believing we could insert ourselves into a chaotic system without altering its configuration, even though I knew that was impossible. That our very presence, even if we did nothing more than breathe in and out, had to change the pattern and alter the outcome."

"But if that's true, then we all did it, and every historian who's ever gone to the past is to blame." She frowned. "But why weren't there indications up to a few months ago? Why did it take forty years?"

"That I don't know. In a chaotic system, not all actions have significant consequences. Some are damped down by other events or absorbed or canceled out. It may have taken that long for enough changes to accumulate for a tipping point."

Like the vases and china and crystal in the china shop, Polly thought. Each crash of the bull against the table, each pounding step, brings them nearer and nearer to the edge, till one last minor nudge takes them over it. That's what Mike and Eileen and I did, that one last tiny nudge. And it brought the continuum crashing down.

But Mike had tried to go back through his drop before he saved Hardy's life. Why hadn't it let him?

"Why didn't-?" Polly began, and realized Mr. Dunworthy was in no condition to answer any more questions. He looked dreadful, and in spite of the fire, he'd begun to shiver again.

"Time to go home," she said. She put money down for the tea and brandy, removed her coat from his knees, and put it on.

When she took his arm, he didn't resist, but let her lead him out of the pub, onto the wet, now-dark street and into a taxi. His hand, as she helped him in, was hot to the touch. "You've a fever. I think I'd better take you to hospital. St. Bart's," she said to the driver.

"No," Mr. Dunworthy said, clutching her arm. "They were very kind to me. They don't ... Please, not the hospital."

"All right, but when we get home I'm telephoning the doctor."

And I'm going to go in first so I can give Eileen some warning, so she won't think he's the retrieval team and get her hopes up.

But he is the retrieval team, she thought bleakly. He came through to rescue me, and now he's as stuck in this morass as we are.

They pulled up in front of the house. "I need to run inside and fetch your fare," she told the driver. "I'll be back straightaway," but he was shaking his head.

"I'd best 'elp you take 'im in, miss," he said. "You'll never manage 'im by yourself." And before she could say anything, he was out of the taxi and helping Mr. Dunworthy out, so she had no opportunity to warn Eileen.

But Eileen seemed to size up the situation instantly. "Can you help us get him into bed?" she asked the taxi driver.

"Who's at?" Alf asked, emerging from the kitchen with a slice of bread in one hand and a spoon in the other.

"Mr. D-" Eileen began.

"Mr. Hobbe," Polly said.

"Is 'e soused?" Binnie asked.

"No, he's ill," Polly said.

Binnie nodded wisely. "That's what Mum allus-"

"Binnie, go turn down the bed," Eileen said.

"Not Binnie. Rapunzel. I've decided my name's Rapunzel."

I am going to kill that child, Polly thought, but Eileen said calmly, "Please go turn down the bed, Rapunzel."

She did, tossing her perpetually untied hair ribbon as if it were Rapunzel's braid, and Polly helped Mr. Dunworthy out of his wet coat and shoes while Eileen ran down to the corner to phone the doctor.

She'd been afraid Alf and Binnie would come in and ask annoying questions, but after a minute of standing in the doorway whispering to each other, they disappeared.

When she came out to hang Mr. Dunworthy's wet shirt on the oven door and put the kettle on, Alf asked, " 'E ain't a truant officer, is 'e? Or a tube station guard?" Which meant they thought they recognized him from somewhere. She hoped they hadn't tried to rob him as he walked to St. Paul's.

"No," she said. "He's Eileen's old schoolmaster."

Schoolmasters were apparently as frightening as truant officers. The two of them didn't even attempt to follow her into his room, though by the time the doctor arrived they were back to their old selves.

"It ain't measles, is it?" Binnie asked. "We ain't gonna be quarantined, are we?"

We already are, Polly thought.

"Is 'e going to die?" Alf asked.

Yes. On or before May first.

"He'll be perfectly fine," the doctor said heartily. "All he needs is to be kept warm and to rest, and he's not to worry over anything. He needs building up, so he's to have beefsteak and eggs-whole, not dried-every day."

"But how?" Eileen said. "The rationing-"

"I'm writing a prescription. Take it to the ration office, and they'll give you the necessary coupons." He handed her the prescription and a paper packet. "And he's to take this powder, dissolved in a glass of water, at bedtime."

"Just like in an Agatha Christie novel," Eileen said, looking at the packet after the doctor'd gone. "That's always how the victim's murdered."

"Who's been murdered?" Alf asked eagerly.

"No one. Go do your lessons," Eileen said, still examining the packet. "But I doubt whether there's anything in this powder for a fever. Aspirin's the only thing which will help."

Nothing will help, Polly thought, but she offered to go to the chemist's for the tablets. "I need to ring the theater and tell them I'm not coming in. I can do that while I'm at the chemist's."

"Oh, I forgot all about your rehearsal," Eileen said. "You could still go. I can care for Mr. Dunworthy."

"It's too late. By the time I got there, the performance would be over. And someone's got to go for the aspirin."

And she needed to get away for a few moments, to think out how she was going to tell Eileen. She would not be upset on her own behalf, but Polly couldn't bear the look Eileen would have on her face when she told her they weren't getting out. And worse, that she wasn't the only one with a deadline. That Mr. Dunworthy had one, too. Soon.

As soon as she reached the chemist's, she rang up the Alhambra. "Your luck's in," Hattie said. "Canning Town got it last night, so Tabbitt hasn't made it in either, but he'll be here tomorrow, so you'd better be. And if I were you, I'd think of a different excuse in the meantime. He'll never believe the one you just told me." There was a pause. "Oh, I've got to go. I'm on. Victory number. Ta."

But there won't be any Victory numbers, Polly thought, feeling her way back to the house through the darkness of the blackout. And what will happen to Hattie when we lose the war? And to the other girls in the chorus?

You know what will happen to them, she thought.

But perhaps it wouldn't come to that. Mr. Dunworthy had said he didn't know if the continuum was collapsing or correcting itself. And there were things in his theory which didn't fit. If their actions had been a threat, why had they been allowed to come through at all? Why hadn't they been prevented from coming in the first place, like Gerald?

And once they were here, why hadn't they been allowed to leave? Mr. Dunworthy had said it was to contain the infection, but if Polly's drop had opened, she wouldn't have stumbled, shell-shocked and stricken, into Townsend Brothers, and Marjorie wouldn't have ended up in Jermyn Street, wouldn't have become a nurse, and if the people on the beach watching the smoke from Dunkirk hadn't prevented Mike from going to his drop, he wouldn't have fallen asleep on the Lady Jane and ended up in Dunkirk and saved Hardy's life. And if Eileen's drop had opened, she wouldn't have been able to keep the City of Benares letter from Mrs. Hodbin; she wouldn't have been there to drive the ambulance on the twenty-ninth and save her passengers' lives.

That was the cruelest irony of all, that they had undone the future out of a desire to help-Eileen's giving Binnie aspirin to bring her fever down and tearing up the letter to keep the children from drowning, Mike's unfouling the propeller because he couldn't stand the thought of fourteen-year-old Jonathan being killed and pushing the two firemen away from the collapsing wall.

Even the act which had set it all in motion had come not from malice but from an innocent desire to see something beautiful. It seemed impossible that compassion and kindness should be the weapons of destruction, that just the opposite should be true. It was true that in a chaotic system, good actions could have bad consequences, but why-?

Polly had the sudden feeling that she knew the answer to that, that it lay just out of reach, like a word on the tip of one's tongue. She stopped on the street and stared into the blacked-out darkness, mentally reaching for it. It had something to do with Alf and Binnie blocking Eileen's way, and the shelter at Holborn- A siren not twenty feet away screamed, and she jumped, startled and then annoyed at the interruption of her train of thought. It had had something to do with the shelter at Holborn ... no, that couldn't be right, Alf and Binnie had been at Blackfriars, not Holborn, but it was Holborn, she was certain of it. Holborn and Mike's missing the bus and ...

No, it was gone. And this raid wasn't going to be one of those times with twenty minutes from alert to bombs. She could already hear planes, and she should get the aspirin to Mr. Dunworthy as soon as possible.

But when she arrived home, he was asleep. Alf was, amazingly, sitting at the kitchen table doing his lessons. Whatever he'd done to the tube station guard or the truant officer must have been something appalling even for him.

Binnie was reading aloud to Eileen from the book of fairy tales. " 'You must be home before the clock strikes twelve,' the fairy godmother told Cinderella, 'or the spell will be broken.' "

"Should I wake Mr. Dun-Mr. Hobbe and give him the aspirin?" Polly interrupted to ask Eileen.

"No, sleep is the best thing for him."

"What does that mean, the spell will be broken?" Binnie asked. "What happens when it's midnight?"

"I'll wager Cinderella blows up," Alf said. "Boom!"

"Go on to bed, Polly," Eileen said. "You look done in."

I am, she thought. We all are. And midnight's coming.

She went to bed, but sleep was out of the question, and when she heard Mr. Dunworthy coughing in the night, she got up quietly, fetched a glass of water, and took it and the aspirin in to him.

He was sitting up in bed. "Oh, good, it's you," he said when she switched on the lamp beside the bed. "I need to tell you something." And whatever it was, it was more bad news, because he had the same hopeless look he'd had in St. Paul's and in the pub.

"First, you need to take these," she said, and while he downed them, she felt his forehead. It was still hot. "You're still feverish. You need to try to sleep. Whatever it is, you can tell me in the morning."

"No," he said. "Now."

"All right," she said, and sat down on the edge of the bed.

He took a deep, ragged breath. "The continuum will go on attempting to correct itself whether it can succeed or not."

Like a vanquished army fighting bravely on, Polly thought.

"And since we're the source of the damage," he said, "and since access to the future is no longer available-"

"It will have to kill us to stop us doing any more damage."

Mr. Dunworthy nodded.

"You think that's why Mike-Michael-was killed, to stop him from altering any more events?"

"Yes."

"And it will do the same to us," Polly said. "Including Eileen."

He nodded.

"When?"

"I don't know. Before the end of the Blitz, I would say. That's its best opportunity. There are a number of large raids between now and the tenth of May."

"But you know where the raids are and where and when the bombs hit, and we can make certain we're in Notting Hill Gate on those nights. It's safe!" she insisted, but even as she said it, she could hear Mrs. Brightford reading Sleeping Beauty to Trot, could hear her reading about the king destroying every spinning wheel in the kingdom, vainly attempting to stop the inevitable.

"Isn't there anything that can be done?" she asked.

He was silent, and she thought, appalled, He still hasn't finished. There's more bad news to come. And how could anything be worse than a death sentence for Eileen?

"What is it?" she asked, but she already knew. Their actions hadn't just affected the course of the war. They'd affected Theodore and Stephen and Paige and Mr. Humphreys. Eileen had kept Alf and Binnie from going on the City of Benares, and Mike had kept Hardy from being killed at Dunkirk. Those alterations would have to be corrected, too.

And how many others? Marjorie? Major Denewell? Miss Laburnum and the rest of the troupe? If she hadn't done that reading of The Tempest with Sir Godfrey, they wouldn't have formed the troupe. They wouldn't have been safely in Notting Hill Gate every night instead of at home being killed, like they were supposed to be.

"It's not just going to kill us, is it?" Polly asked, her throat dry with fear. "It's going to kill everyone we've come into contact with, isn't it?"

"Yes," Mr. Dunworthy said.

Are these the shadows of the things that will be, or are they shadows of things that may be, only?