Rajiv stared at the hex dump. The header was alien: IDX3 followed by a timestamp from 1997. He tried the standard tricks—renaming it to .txt (gibberish), forcing VLC to open it (crash), feeding it to a Python script (silence). The file was a lock without a key.

That afternoon, his boss called him in. "The architect," he said, "wants to know if you can recover the rest. She's offering double. What do we tell her?"

AutoCAD opened. And there it was.

In the fluorescent-lit cubicle of a mid-level data recovery firm, Rajiv was known as the ghost. He never spoke at happy hour, never changed his desktop wallpaper from the default blue, and never, ever asked for help. His specialty was the graveyard of file formats: the orphaned, the legacy, the "what the hell is this?" extensions.