A dark, atmospheric, and professional audiobook cover illustration in a square 1024x1024 format. The style should evoke classic mystery and ancient Egypt, with a touch of art deco or noir influences. The central imagery should be a stylized, antique Egyptian ankh (cross) that appears to be crafted from aged bronze or dark gold, subtly glowing with an inner, mysterious light. Surrounding the ankh, or subtly incorporated into its design, are faint, ghostly hieroglyphs that hint at secrets and ancient knowledge. The background should be a deep, velvety indigo or obsidian black, with very subtle, diffused smoky tendrils or faint, shimmering dust motes that create a sense of depth and intrigue. No text, no letters, no words, no title, no author name whatsoever. The mood is enigmatic, suspenseful, and intellectual. The lighting should be dramatic, with strong chiaroscuro, casting long, mysterious shadows from the ankh. The overall composition should be balanced, professional, and immediately recognizable as a premium mystery audiobook cover.