Leo thought it was a glitch. He opened a new file.

Leo’s hands shook as he checked the file properties. Creation date: . Last modified: today, 2:00 AM . Author field: “AUTODESK.AUTOCAD.V2020.WIN64-ISO” – but below it, in metadata he’d never noticed, a second author: “The previous owner.”

His heart thumped. He zoomed in on the tunnel. At its end, someone—or something—had drawn a door. No, not a door. A vault. Circular, like a bank vault, but old. Victorian. And behind it, a single annotation in a script he didn’t recognize: “Here lies the original architect. He forgot to pay.”