“But how could we? Historians can’t alter events,” Eileen said innocently. “Can they?”

“No,” Mike said. “She just means it’ll be tough to get Phipps out with all the security they’re bound to have.”

But as soon as he got Polly alone for a moment, he asked her, “What’s happened? Did you find a discrepancy while I was gone?”

“I don’t know. Marjorie—the shopgirl I worked with at Townsend Brothers and who Eileen told she worked at Padgett’s—is enlisting in the Royal Army Nursing Service.”

Which made no sense at all. He sat her down and made her explain it to him. When she finished, he said, “But lots of women enlisted.”

“But she said she enlisted because of having been rescued from the rubble, and she wouldn’t have been in the rubble if it hadn’t been for me.”

“You don’t know that,” he said. “She might have eloped even if nothing had happened to you.”

“But that’s not all,” she said, and told him about the UXB at St. Paul’s. “Mr. Dunworthy said it took three days to get it out, which means it should have been removed on Saturday, not Sunday.”

“No, it shouldn’t,” he said, relieved that that was all. “It’s not a discrepancy.”

“You don’t know that.”

“Yes, I do. While I was looking for you, I went to St. Paul’s. I figured any historian of Dunworthy’s would have heard all about the cathedral from him and might show up there, and you did, just not on the same day as me. And anyway, this old guy who worked there—”

“Mr. Humphreys?” Polly said.

“Yeah, Humphreys. He gave me a tour of the whole place—sandbags and all—and told me all about the UXB. And he said it hit the night of the twelfth, which would make it three days if they got it out Sunday afternoon. So there’s no discrepancy there, and lots of women eloped with enlisted men during the war. And the increase in slippage would make it harder for us to alter events, not easier.”

“But if that isn’t what’s going on, and we can affect events—”

“Then Phipps has no business being at Bletchley Park, and the sooner we get him out of there, the better. If he’s still there. If he went through just after his recon and prep, he might already have gone back.”

“I don’t think so,” Polly said. “His joke about the water-soluble ink makes me think he’s probably there to observe the cracking of the naval Enigma code, and they didn’t capture U-boat 110 and get the bigram books until May of 1941.”

Great, Mike thought. Phipps would have six months to louse up the war. If he hadn’t already. Maybe that was why their drops wouldn’t open. It wasn’t something Mike had done—it was Phipps’s fault.

Mike didn’t say that. He just told them he intended to leave for Bletchley right away. “Shouldn’t we both go?” Eileen asked. “I know what Gerald looks like. And with two of us, we’ll be twice as likely to find him. We can split up—”