“That’s all right, I can take it.” With a smile for her friend, she snatched at the paper he pulled from a stack of them and spun for the codebook.

“What can I do to help?” Drake pulled her chair out for her.

“I don’t know yet. Give me a moment.” She set everything up as she always did. The cypher, the message, scrap paper, a sheet to write the decrypt on, a pen. “Analysis, perhaps. You’ve been doing enough of that.”

“Will it bother you if I look over your shoulder as you work? The faster to see what appears?”

She shook her head. They often worked as a team in here, looking at the same papers, correcting one another, contradicting one another. “Not a bit.”

The message was longer than the others had been. Long enough that it made her chest tighten. How much time did they have? Midnight, he’d said. What happened at midnight? They didn’t have but three hours now until they found out.

She got to it. She only paid attention to the first words, enough to be sure they were coherent, proof that she was using the right code. But after that she ignored the actual meanings and focused on the details. Encrypted word to number, number to German word, German word to English word.

“He’s describing a location.” Drake leaned an elbow onto her desk. “‘Follow the Thames inland . . . when the river turns ninety degrees toward the south, watch for a cluster of church steeples.’ Have we a map of London and the surroundings around here anywhere?”

“Hall has one, I believe,” de Grey said.

Drake patted her shoulder. “I’ll be right back.”

“Mm.” She kept working while he was gone. And it must have taken him quite a while to find what he was looking for, because she was penning the last word into place when finally he came back into the room, Hall himself a step behind him. Drake spread the map on an unused desk and began tracing a finger along it.

“What comes after the part about the steeples?”

She read it to him, turning on her chair to better face him. “‘This is the northmost apex. Follow the river another seven kilometers—’”

“That would be Woolwich.” Drake glanced up, face grave. “Keep reading. But I have a feeling I know where he’s leading them.”

She finished, up to “‘this is your mark,’” watching his finger trace along the map as she did so. The question already burning her tongue. “Is that where he told you to go? Where he has Dot?”

He nodded toward the decrypt. “Is there anything else?”

There was, and it made her pulse slow to a dull throb. “He says he recommends no fewer than two dozen Gothas set out to ensure that at least five reach the mark.”