In the novel ‘The Palermo‘Ambush’ by Collin Forbes the plot is an Alied mission to use the aid of the Maffia (Cosa Nostra) against the Axis. Did the Alies make a deal with the Maffia to gain their aid during the invasion of Sicily?
That’s the story; I’m not entirely sure how much of a ‘deal’ was made. It was in the Cosa Nostra’s interest to get the Germans out, and get the Americans (in particular) in - mostly because the Americans had more stuff to steal. Before the invasion, the mafia would have only been able to provide maps and such.
It is pretty clear that Charlie “Lucky” Luciano cooperated with the US Navy’s Office of Naval Intelligence and the OSS to maintain “labor peace” on the docks of the East Coast. The mob-controlled unions would not have helped the Germans, but might have slowed down or held up cargo going overseas.
In return, Luciano was moved from Dannamora to the much nicer Great Meadow prison, and allowed to meet freely (and without records kept) with “associates” from outside while in prison. After the war, Luciano will be freed but deported to Italy (at his request.). All official records of any deal were collected and destroyed by the ONI.
This sounds like a great Spies & Ties story
For a real down-the-rabbit hole version that ties three different conspiracy theories, check out “Brass Target” (1978) - based on “The Algonquin Project” (1974) which I haven’t read. In the movie, a CIC officer (John Cassavetes) investigates the robbery of “the Reichsbank gold”, which includes a plan to kill Patton, and involves Lucky Luciano to provide a hit-man. With George Kennedy as Patton, Robert Vaughn and Edward Hermann as Americans who are up to something, Max von Sydow as a shadowy Swiss… something or other, Patrick McGoohan with an atrocious attempt at an American accent, and Sophia Loren playing… well, Sophia Loren, it’s a great caper movie set in late-1945 in occupied Germany.
Douglas Valentine has written quite a bit about this, especially in The Strength of the Wolf. Alfred McCoy brought it up in The Politics of Heroin.