A minimalist, atmospheric audiobook cover design. The central image is a single, elegant, antique brass key resting on a dark, polished wooden surface. The key is slightly angled, catching a subtle, dramatic spotlight from above, creating a strong shadow that stretches across the wood. The mood is mysterious and suspenseful. The color palette is dominated by deep, rich browns of the wood, the metallic sheen of brass, and stark, deep shadows with a subtle hint of a cool, almost imperceptible blue in the shadowed areas, suggesting a hidden depth. The overall composition should evoke a sense of unease and intrigue, hinting at secrets waiting to be unlocked. The aesthetic is sophisticated and modern, suitable for a psychological thriller. Square format, 1024x1024 pixels. No text or logos.