Fidel Castro took power in 1959 and by 1963 the CIA was getting so desperate to end the life of the Cuban leader that they were willing to go to the Mafia. They contacted American mobsters and offered to pay them a substantial sum if they managed to kill Castro. The Mafia took the job and headed to Cuba.
The Mafia came up with a plan that involved poisoning, believing that it would be the best way to kill Castro without getting caught. They told the CIA that they wanted a pill that would be odorless and tasteless that would be strong enough to quickly kill Castro. The CIA complied and delivered a pill that met the demands of the Mafia.
The Mafia decided that they would do the job at the cafeteria of the Havana Libre Hotel. Castro came to get a chocolate milkshake and the hired assassin waiter was to retrieve the pill from where it had been hidden in the freezer. However, when the waiter attempted to retrieve the pill, it stuck to the side of the freezer. It so frozen to the side that as the waiter pulled on the pill to remove it, the pill ripped open.
Fabian Escalante was the intelligence chief for Castro and he recounts that this milkshake attempt was the closest that anyone got to kill Castro. Over the course of several decades, Escalante managed to save Castro from hundreds of assassination attempts through his network of spies in Cuba and around the world. Escalante developed such a reputation protecting Castro and Cuba that a television series was produced that dramatized his life.