The escalation took four days.
Marcus knew something was happening in those four days because Pemberton called him — directly, personal mobile, first time since the Argus briefing — and asked him a series of questions that were careful, specific, and clearly oriented around establishing a timeline.
When had Marcus first made contact with the facility? When had the Phase Two briefing occurred? Who, in Marcus's accounting, had been in the room at each major meeting? Had Marcus shared any information about the Depth project's scope with anyone outside the engagement?
Marcus answered every question accurately and completely. He noted that the last question contained an implicit inquiry about Threadline's team and said so directly: "You're asking whether I told my team about Phase Two."
"Yes," Pemberton said.
"I told them the engagement existed and that it had a classified component. I did not describe the scope or the subject matter. Priya, Jin, Amir, and Yuki know I do advisory work for a federal entity. They don't know what I'm building or what it's for."
"Are you certain?"
"I'm certain about what I told them. I'm certain about their integrity. I can't give you absolute certainty about what they might have inferred from working in proximity to me." A pause. "If your concern is that someone on my team is the source — I don't believe it. But I can't give you a certainty I don't have."
Pemberton was quiet. "Fair," he said. "I'll be back to you."
The call ended.
Marcus sat with the conversation. He thought about Yuki's monitoring, Priya's careful questions, Jin's uncomplicated trust, Amir's professional self-containment. He thought about each of them as a system, the way the System had taught him to think about everything — not with suspicion but with precision.
He did not believe any of them was the source. He believed this not out of loyalty but out of analysis: none of them had access to the specific information Welch had demonstrated, and none of them had a visible connection to Sorokin's network.
Which meant the source was inside the working group. Or adjacent to it.
He thought about Warren's file on Sorokin. He thought about the document in Pemberton's locked drawer — the oversight assessment with Dr. Park's dissent. He thought about the forty-three analysts doing manual reconciliation work before the semantic layer had automated it.
Forty-three people who had seen the classified data. Any one of whom might have been in place before Marcus arrived.
He opened a blank document and started thinking through the access architecture of the Depth project — who had seen what, in what sequence, with what logging. He was not going to hand this analysis to Pemberton without being certain of it, but he was going to have it ready when it was needed.
He worked for three hours. When he was done he had a seven-page document that laid out the access architecture precisely, with three plausible vectors for information to have reached Sorokin's network, ranked by probability.
He encrypted it and saved it in two places.
Then he called Elaine.
"I have an access architecture analysis for the Depth project," he said. "I've identified three probable leak vectors, ranked. Do you want it?"
A silence. "You did this analysis yourself."
"Yes."
"When?"
"This afternoon."
"Marcus." Her voice had the quality it had taken on in the Arcline meeting — that heightened focus. "Send it to me. Not through the facility channel. Through Marsh."
"Why through Marsh?"
"Because if the leak is inside the working group, I don't want this document in the facility's document management system until I know who's reading it."
He understood immediately. "I'll have Marsh send it within the hour."
He called Marsh. She received the document, reviewed it, and transmitted it to Elaine through her own secure channel. She called Marcus afterward.
"The analysis is good," she said. "Thorough. Your second vector — the analyst team access to the semantic layer's test environment — that's the one I would focus on first."
"That was my read too."
A pause. "You're operating quite far outside the boundaries of your original engagement."
"The boundaries of the original engagement didn't account for a leak to a foreign intelligence operation," Marcus said.
"No," she said. "They didn't." Another pause. "Be careful about how far you extend beyond the NDA's scope. You're doing things that are helpful and possibly necessary. You're also doing things that could be framed, by people who wanted to frame them that way, as operating outside your authorized access."
"I know."
"Keep me between you and any action that isn't pure analysis."
"Always."
He hung up and went back to thinking about the three vectors. And, specifically, about who was best positioned to determine which one it was.
He thought about Yuki, who had built a monitoring system for Vektor Systems' public footprint in four days. He thought about the sealed test environment where the semantic layer had been integrated with the classified data.
He thought about whether there was a passive monitoring approach for internal access patterns that would generate evidence rather than just inference.
There was.
He opened a new document and started designing it.