“I was able to save his life because I was here, because none of our drops would open. I think we may have been wrong about why they’re not opening, and about the slippage. What if it’s not to prevent us from altering the course of history? What if it’s to put us where we can? To keep us here until we do?”

She reached forward and took his hands in hers. “What if by colliding with the Wren, you saved her life instead of causing her death? What if she was on the way to meet the Wren who was killed, and because you delayed her, she wasn’t there when the bomb hit? Or what if you saved the life of the naval officer? Or the man in the black suit? Was he going toward St. Paul’s or coming from it?”

“Toward St. Paul’s.”

“Then he might have been a member of the fire watch going on duty, and on the twenty-ninth he found one of the incendiaries and put it out, and if you hadn’t run into him, St. Paul’s would have burned down. And Alf and Binnie were what made you run into him.”

“But—”

“Mike saved Private Hardy’s life because the slippage caused him to arrive in Saltram-on-Sea too late for the bus. And I met Sir Godfrey because the net sent me through in the evening instead of the morning.” She told him about being caught by the warden and taken to St. George’s. “And because of the slippage that first time you came through, you ended up at St. Paul’s Station. Where you needed to be to run into the Wren.”

“So you’re saying slippage’s function is to bring about alterations, not prevent them? That it kept us here intentionally?”

“I know what you’re going to say, that a chaotic system isn’t a conscious entity—”

“That’s exactly what I’m going to say.”

“But it wouldn’t have to be. You thought the shutting of our drops was a defense mechanism. Perhaps it is, only not to shut off interference from the future, but to enlist it when the continuum’s threatened. If Hitler’d won the war, he’d have had time to develop the atomic bomb, and he wouldn’t have hesitated to use it against the United States and all the other non-Aryan peoples. He already had a plan in place for wiping out Africa’s ‘mud people,’ and he wouldn’t have stopped there. He could have ended by wiping out—”

“Everything,” Mr. Dunworthy said. “Götterdämmerung, the twilight of the gods. But if that’s the case, and the continuum wanted to protect itself, why didn’t it simply let us come through and shoot Hitler?”

“I don’t know. Perhaps the system only allows minor changes. Or unintentional ones. Or perhaps something else is going on in those divergence points which makes it impossible to alter them. Or perhaps we came into the picture too late. Like the Good Fairy in Sleeping Beauty—”

“The Good Fairy?”

“Yes,” she said earnestly. “She couldn’t undo the spell, she could only make it less terrible. Time travel wasn’t invented till long after the start of the continuum. Perhaps we’re too late to completely repair it, but we can still—”