Vargas’ cry of surprise and alarm told me all I needed to know. My hold-out weapon had worked! When I’d paused at the bottom of the stairs that led to the teocalli, I had cracked the lid of the organ-transfer case and poured half of the contents of the perfume bottle inside. The lining of the case was soaked with gamma scopolamine—which had mixed with the blood that was smeared on the gel pack and thus become invisible. Vargas had touched it as he tore open the plastic lining to see if the head was really inside . . .