As Langdon's gaze began to trace the inlay, his eyes stopped short on an unexpected object lying on the floor just a few yards to his left, surrounded by police tape. He spun toward Fache. "Is that... a Caravaggio on the floor?"

Fache nodded without even looking.

The painting, Langdon guessed, was worth upward of two million dollars, and yet it was lying on the floor like a discarded poster. "What the devil is it doing on the floor!"

Fache glowered, clearly unmoved. "This is a crime scene, Mr. Langdon. We have touched nothing. That canvas was pulled from the wall by the curator. It was how he activated the security system."

Langdon looked back at the gate, trying to picture what had happened.

"The curator was attacked in his office, fled into the Grand Gallery, and activated the security gate by pulling that painting from the wall. The gate fell immediately, sealing off all access. This is the only door in or out of this gallery."

Langdon felt confused. "So the curator actually captured his attacker inside the Grand Gallery?"