The small brass timer sat on the glass counter, its dark needle ticking loudly in the quiet room. Each sharp tick sounded like a heavy hammer hitting a stone.

The eccentric old collector picked up a small pair of iron tongs with his thin fingers. He held the sleek silver fountain pen right above a small iron pot filled with boiling chemical acid. The hot acid bubbled quietly, releasing a faint white smoke that smelled sharp and dangerous.

"Five minutes, Mrs. Vance," the old man said with a cold, mocking smile on his thin face. "Identify all three hidden structural errors in this ancient cathedral model, or your father's heirloom...