A professional, atmospheric book cover design for a classic mystery thriller. The composition features a dimly lit, narrow cobblestone alleyway in old Bucharest at twilight. In the foreground, a shadowy, distorted silhouette of a man with a hunched back is seen cast against a weathered, peeling plaster wall. A single vintage street lamp casts a dramatic, high-contrast golden-yellow glow, creating long, sharp shadows. The color palette is composed of deep midnight blues, moody grays, and warm, flickering amber. The style is noir-inspired, cinematic, with a grainy, high-quality film texture. The imagery should be evocative and mysterious, focusing on architectural details like rusted iron gates and foggy air. No text, no letters, no words, no title, no author name, 1024x1024 square format.