Seven-time Oscar nominee Richard Burton continues to have an intriguing afterlife, four decades following his death. At this year’s BAFTA awards, a movie about his early life, Mr. Burton, earned a nomination for best British Film. Mr. Burton, directed by Marc Evans, was also one of the audience favorite films at January’s Palm Springs International Film Festival. It opens in theaters this week and, aided by a strong cast, should appeal even to audiences who have fuzzy recollections of the once notorious actor.

The film begins with a quotation from Elizabeth Taylor (who married Burton twice after a scandalous, heavily publicized affair that began during the shooting of Cleopatra in 1962). In it, Taylor states that Richard never would have found fame and fortune without the efforts of his adoptive father, Philip Burton (superbly played by Toby Jones in the film). Richard (Harry Lawtey of Industry) was actually born Richard Jenkins, the son of a Welsh miner who abandoned the family after the death of Richard’s mother. Richard was then raised by his older sister and her husband, but his talent was spotted by his teacher, Philip Burton, who recognized the young man’s appreciation of literature and drama.

Philip Burton was himself an aspiring writer who penned some dramas for the BBC and had a number of contacts in the theater. But the film suggests that he felt disappointed by his progress and may have compensated in part by playing a mentorship role to Richard. Whether he also felt a physical attraction to young Richard is treated subtly and never definitively answered in the film.

Opening scenes contrast the comfortable but modest living conditions of Philip, who resides in a boarding house owned and overseen by a sympathetic landlady (trenchantly played by Lesley Manville), and the tension in Richard’s household. His brother-in-law demands that Richard drop out of school to contribute to the family finances; the boy resists following his father into the mines but gets a job at a clothing store instead.

Eventually Burton comes up with the idea that Richard can move into the boarding house and return to school, but this may require Burton adopting Richard as his son. Richard is comfortable with this arrangement, and Philip suggests that Richard may have an opportunity for a fellowship to study acting at Oxford. But when Richard’s father and fellow students suggest that Philip may have something more than a paternal interest in the handsome young aspiring actor, Richard flees in terror.

It is to the film’s credit that it refuses to come to any definitive conclusion about Philip’s interest in Richard. There was never anything overtly untoward about their close bond, and until the end of his life, Richard continued to express gratitude for Philip Burton’s mentorship. Yet it may be significant that we never see any hint of Philip’s romantic or sexual interest in women. Richard did leave Burton’s household for several years, but when he had his breakthrough role in Stratford in 1951, portraying Prince Hal in Shakespeare’s Henry IV plays, Philip returned and (at least in this telling) helped Richard to a triumphant opening night.

Richard Burton quickly moved on from there. He earned his first Oscar nomination in 1952 for My Cousin Rachel, and in 1954, he starred in the first Cinemascope epic, The Robe. (Other memorable roles included Becket and Who’s Afraid of Virginia Woolf?, his finest collaboration with Taylor.) Burton also continued acting in theater, and the 1964 production of Hamlet, in which he starred under the direction of John Gielgud, remains perhaps the most phenomenally successful production of the play in modern theatrical history.

Since unknown backstories behind startling successes always compel, Mr. Burton has a lot going for it. Lawtey doesn’t quite match Burton’s thrilling vocal delivery (who could?), but he convinces us of the young actor’s talent and potential instability. But it is really Jones, in one of the finest performances of his long career, who holds our attention throughout the movie. The subject of mentorship is not treated frequently onscreen, but Mr. Burton may be remembered as one of the definitive explorations of the theme. All the technical credits help to ground the film — cinematography by Stuart Biddlecombe is especially striking — but it is the performances that truly mesmerize.