Rain lashed against the darkened library windows, obscuring the already fading twilight beyond their panes. A single, flickering desk lamp cast long, eerie shadows across the dusty, leather-bound volumes of arcane lore. Professor Armitage lay sprawled beside an overturned, ornate mahogany table, his spectacles askew and coat askew. A crimson stain bloomed visibly upon his crisp white shirtfront, a stark contrast to the room's muted tones. The heavy scent of old paper mingled with the metallic tang of freshly spilled, life-ending blood. No sign of forced entry suggested a trusted killer had gained access to this secluded study. Detective Harding surveyed the grim scene with a practiced, weary gaze, his mind already piecing together fragments. He noticed a single, white feather delicately resting near the professor’s lifeless, outstretched hand.