Clint Eastwood's The Mule is based on the true story of an elderly World War II veteran who ultimately becomes the oldest and one of the most prolific drug mules in the history of the United States. Primarily starring Eastwood as Earl Stone and Bradley Cooper as DEA Special Agent Colin Bates, with Laurence Fishburne, Michael Peña, Ignacio Serricchio, Dianne Wiest, and more rounding the supporting cast, The Mule follows a horticulturist and Korean War veteran who earns money transporting drugs after his business goes under.
In The Mule, Earl Stone was once a prominent member of the horticulturist community and an award winner thanks to his daylilies, but the widespread adoption of the internet forced him to close down and not only lose his business but his home as well. But because he's a cautious driver who's never been pulled over in his life, he's recruited to deliver drugs through Illinois for a cartel. Although he's successful, he's eventually caught by the DEA and sentenced to prison. All of this was inspired by the New York Times article "The Sinaloa Cartel's 90-Year-Old Drug Mule", which chronicles the investigation into the drug courier with quotes from the federal agent who arrested him.
Eastwood's Earl Stone is based on Leo Sharp, who was known within the Sinaloa Cartel as El Tata. Sharp was an aging World War II veteran who became a pioneering horticulturist after his airline business failed, particularly working with daylilies. But when that business started to fall by the wayside, too, he was recruited into drug trafficking and was so good at it that he became somewhat of a myth within the cartel. In the end, he was arrested by the DEA and sentenced to three years in prison, of which he served one.
In The Mule, Eastwood's Stone is also a war veteran-turned-horticulturist who turned to drug-running after his business went south, but rather than having fought during World War II, the character is supposed to be a Korean War vet. Interestingly, though, Stone makes several remarks about Nazis, particularly to Serricchio's character. Given the timeline of The Mule, it makes sense that the film moved up the war from WWII to the Korean War in order to retain the character's age. While he was transporting drugs for the cartel, Stone also went by the codename Tata. However, he only made about a dozen runs in total over the course of several months, not almost ten years as was the case with Sharp.
Cooper's Agent Bates is based on real-life DEA Special Agent Jeff Moore, who caught Sharp in 2011. While Stone's arrest in The Mule was quite dramatic (for obvious reasons), Sharp's arrest happened practically the same way, being caught on an interstate highway while driving a Lincoln pickup truck. After being arrested, Sharp pleaded guilty to the charges but attempted to avoid actual jail time by offering to pay his fine by growing Hawaiian Papayas for the US government. Stone, meanwhile, fully accepted responsibility in the film. In both cases, Sharp/Stone was able to maintain his daylily farm while in prison.
While The Mule is inspired by a true story, there are obvious changes to the narrative. Eastwood's Stone is purely fictional, and how he lived his daily life is something that was conjured up for the film. Only the crux of the true story remains, which is that Sharp was an elderly war veteran who began transporting drugs across the midwest after his flower business collapsed. Sharp passed away shortly after he was released from prison due to his deteriorating health. While it's fair to presume the same fate befalls Eastwood's Earl Stone at the end of The Mule, the film leaves that part of the story ambiguous.