The title refers to criminal Rafael Delgado, an expert diamond thief. He's involved with a band of criminals, who dress in British style (bowler hats and umbrellas) but who speak Italian. It's implied they are Mafia types trying to pass themselves off as British. Delgado, even while in prison, has pulled off a stunning robbery with the help of the gang. So many diamonds are missing it could affect the world's economy.