Naples: Raffaele, a cafe musician, is cajoled into performing a night-time serenade outside an apartment block. However, his mandolin playing is rudely interrupted by gunshots and a falling Jamaican man, who plummets from a window above. A camp character is also ejected from a window and Raffaele is compelled to conduct his own investigation. It transpires that a celebrated maestro, Victor Navarro is being blackmailed. Lucia, Navarro's attractive daughter-in-law, was present at each murder. The amateur detective is drawn to her and becomes embroiled in a mystery involving death threats and a macabre secret...