Sister Agnes pushed open the heavy, creaking door to the hidden chamber beneath the sacristy. The air within was thick and cool, smelling of damp stone and something else, something subtly sweet and musky. Her eyes, still slightly dazed from the confessional's aftermath, struggled to adjust to the dimness. A single, flickering candle cast long, dancing shadows across the walls, illuminating what looked like a makeshift altar. But it was no altar for prayer. A plush velvet cloth, undoubtedly stripped from a holy table, now covered a low, stone slab in the center of the room. A cruet, normally holding communion wine, now contained a clear, amber liquid that glinted...