Given the preponderance of ads by political candidates this season during the midterm elections, perhaps you missed the trailer for the movie “Green Book,” which is slated for release later this month. Most folks knowledgeable about “The Negro Motorist Green Book,” a travel guide of safety for Black Americans venturing by car through the Jim Crow South, might wonder how a guide could become a movie.

The film has less to do with “The Negro Motorist Green Book” than with a musician who defied some of the book’s advice and warnings, choosing to mark his own path through the dangerous and treacherous backroads. Pianist Don Shirley, the intrepid artist, is the film’s protagonist and during his concert tour of the South, he is driven by a white chauffeur.

That may sound, at first blush, like a “Driving Mr. Daisy,” but there is much more to it than that, and I depart from any further discussion of the film to focus on Shirley’s life and legacy, which is sure to give the film a number of exciting and provocative moments, both musically and cinematically.

Born Donald Walbridge Shirley in Pensacola, Fla., Jan. 19, 1927, he was a musical prodigy of Jamaican heritage who began playing the organ when he was 3. His father was an Episcopal priest and his mother a teacher, who died when Shirley was 9. It was at the Catholic University in Washington that he began a serious study of music.

He was 18 when he made his professional debut with the Boston Pops, performing Tchaikovsky’s Piano Concerto No. 1 in B-Flat Minor. What began as a promising career in classical music was soon disrupted when told that there was little chance of him, as a Black pianist, succeeding in the classical world. A noted impresario advised him to pursue a career in jazz or popular music, where his race would be less a burden and more acceptable.

This advice was very disconcerting, but Shirley took the admonitions and began devoting himself to performing in nightclubs, investing the American song book and standards with flourishes of the classical background that would distinguish his style. Normally, during the nightclub dates, he performed with a trio, sometimes including a cello. Although his music was entertaining and warmly received, Shirley preferred the stage, where his orchestral interpretations of pop songs could soar beyond the chatter, the smoke and the tinkling of glasses.

As an artist on the Cadence label, Shirley recorded several albums in the ’50s and ’60s that brought a bit of popularity, and certainly enough money to keep him from being the starving artist. Among his recordings were “Don Shirley Plays Love Songs,” “Don Shirley Plays Gershwin” and “Don Shirley Plays Don Shirley.” By the ’60s he had switched to Columbia records.

In 1974, by now fully immersed in a jazz motif despite the classical dismissal, Shirley composed “Divertimento for Duke by Don,” a symphonic work dedicated to Duke Ellington that was performed by the Hamilton Philharmonic Orchestra of Ontario. Inspired by James Joyce’s “Finnegan’s Wake,” he later composed a lovely tone poem.

Shirley’s impulse to weave strands of classical music into his style was by no means unique, but he did it with a personal touch that was, as he said, “transcriptions”—and not a redo of Broadway tunes into a classical mode. In effect then his approach, according to several musical experts, was to provide a “variation on a theme.” For example, “Lullaby of Birdland,” a George Shearing standard, could suddenly morph into a Bach-like fugue, or Irving Berlin’s “Blue Skies” into a tonal rainbow of themes with a variety of musical expressions that have you waiting in vain to hear the familiar melody. Even so, Shirley disparaged any notion of improvisation and this attitude was perhaps consistent with his love-hate relationship with jazz.

No matter the tune, Shirley applied a sweeping wash of sound, and his virtuosic chops are clearly discernible as he glides effortlessly from one end of the piano to the other. Once back onstage, he was in his element, and that occurred almost regularly at Carnegie Hall, above which he lived in an apartment.

One of the best discussions of his music was by Peter G. Graves in The New York Times. “The silky tone and supple rhythmic flow of Mr. Shirley’s playing is just as artful and ingratiating as ever,” Graves wrote of a concert at Carnegie Hall in 1971. “‘I Can’t Get Started,’ heard as a Chopin nocturne, or ‘Blowin’ in the Wind,’ heard as a Rachmaninoff étude, might strike some as a trifle odd, but these—and everything on the program, in fact—were beautifully tailored to spotlight Mr. Shirley’s easy lyrical style and bravura technique.”

Not one to bite his tongue, Shirley told a reporter, “I am not an entertainer. But I’m running the risk of being considered an entertainer by going into a nightclub because that’s what they have in there. I don’t want anybody to know me well enough to slap me on the back and say, ‘Hey, baby.’ The Black experience through music, with a sense of dignity, that’s all I have ever tried to do.”

That dignified demeanor and artistic pride, so much a part of his music, came to an end April 6, 2013, in Manhattan. He was 86.