Before his death, the jeweler wrote a will in which he mentioned the famous diamond "Abbas Shah." But when the heirs discovered his personal safe, the diamond was not there. Without hesitation, they turned for help to the detective Drongo, who, as everyone knows, is able to unravel the most mysterious thing. The detective immediately established a circle of suspects and began to screen out those who had an iron alibi. But suddenly his list began to decline for a completely different reason - someone began to kill the suspects one by one...