Mr. Solo started out as a boxer and head waiter in New York City before becoming the head of the Unione Siciliano.
In June 1957, Solo collaborated with gangsters Helmut M. Springer, Jed Midnight, Jack Strap, Billy Ring, and Pussy Galore. All of the gangsters had been selected by SMERSH treasurer Auric Goldfinger, codenamed as "Mr. Gold", to rob Fort Knox in Kentucky.
During the robbery, where Pussy Galore and her gang impersonated nurses, Jed Midnight's men impersonated Red Cross doctors, while Midnight, Mr. Solo, Billy Ring and Jack Strap wore robes signifying their status as senior physicians to falsely mirror their leadership status.
After the raid failed due to James Bond's message to Felix Leiter, Goldfinger personally executed Mr. Solo by gunshot, along with other mob bosses he hired for the job.
Mr Solo is described as being a big, strong man with dark hair, a big nose, and a "dark, heavy face, gloomy with guilt and many sins". He wears thick, horn-rimmed spectacles, and is a big, chunky man. He cleans his nails with a pocket knife.
- The Unione Siciliano, later renamed the Italian-American National Union, is a real-life Sicilian-American organization that became corrupted by the power of the Mafia. However, unlike the novel, this organization was based out of Chicago, not New York City.
- While Mr. Solo maintains his part in the plan in the novel, he tries to back out in the movie, and is shot and killed by Goldfinger's manservant Oddjob. In the novel, this role is given to Helmut Springer.