The Vigil Candle

You have slipped inside the Chapel of Orn before the tide comes up to swallow the causeway. The door swings shut behind you. Candles gutter in a row along the altar rail, and you can feel in the stone floor a low hum you cannot name. Three niches stand in the east wall, each carved to hold a relic — but only two hold anything, and the third is wrong. Something has been moved, or swapped, or hidden. You are not certain you were meant to notice.