“We didn’t design it that way, Marcus,” I said. “You know the physical blueprints we signed off on last week are correct.”

“I know that, and you know that,” Marcus replied. “But the city inspector only cares about the database. Someone modified the central BIM file three hours ago.”

“I am looking at the digital signature right now,” I said, looking over at Julian, who stood close enough to hear the speaker. “The upload came from an external administrative key.”

“Can you prove it wasn’t an internal error?” Marcus asked. “Because if this is on us, the city will pull our license by morning.”

“Keep the crew on-site but hold the concrete trucks,” I told him. “Do not let anyone touch the structural piers until I upload the verified master file.”

“How long do we have?” he asked.

“Give me one hour,” I said. “I am sending you the cryptographically signed backup now.”

I ended the call and tapped the screen, transferring the original, unaltered design file to Marcus’s secure terminal.

Julian watched me, his glass of scotch catching the amber light of the chandelier.