You won’t find much subtlety in the solid period-piece drama “Marshall,” but you will find plenty of crowd-pleasing courtroom theatrics, some wonderful performances from the main players — and yes, all sorts of reminders of how far we’ve come in terms of race relations since the early 1940s, and how very, very far we still have to go.

Chadwick Boseman is now three-for-three in playing 20th century legends. (And Boseman’s profile will no doubt continue to rise with him cast as Black Panther in the Marvel Universe.) His star power was established with his stellar portrayal of Jackie Robinson in “42” (an historical drama set only a few years after the timeline of “Marshall”), and he was outstanding as James Brown in “Get On Up.”

As the young Thurgood Marshall, a brilliant and passionate civil rights attorney who will be the first to tell you just how good he is (and he wouldn’t be bragging because it’s the truth), Boseman delivers perhaps his finest work to date — even when the material falters a bit and is more heavy-handed and pound-the-point-home than necessary.

Directed by Reginald Hudlin (“House Party,” “The Ladies Man”), who at times can’t resist the urge to stage comically rewarding but obviously exaggerated confrontations and payoffs, “Marshall” is not a sweeping epic about the life and times of the legendary Thurgood Marshall, who argued the landmark Brown vs. the Board of Education case in 1954 and became the first African-American justice of the U.S. Supreme Court in 1967. Rather, it’s a courtroom thriller inspired by the true story of a sensational and incendiary case that proved to be a pivotal moment in Marshall’s career.

The year is 1940. In a case with cinematic echoes of the (entirely fictional) story of “To Kill a Mockingbird,” the NAACP sends Marshall to Connecticut to defend Joseph Spell (Sterling K. Brown), a black chauffeur accused of raping and trying to murder his employer, the socialite Eleanor Strubing (Kate Hudson).

Marshall doesn’t have a license to practice law in the state of Connecticut, but the judge (James Cromwell) rules he can sit at the defense table and offer notes and counsel to Joseph’s attorney — as long as he doesn’t speak a single word.

Through a series of contrivances we needn’t bother to outline, a local civil attorney with no criminal defense experience, Sam Friedman (Josh Gad), is essentially given no choice but to represent Joseph, with Thurgood guiding him every step of the way.

At first Sam wants nothing to do with the case and he explores every possible avenue to get out of it — but as a Jewish man living with his family in a community where there’s no shortage of anti-Semitism, during a time when a monster in Germany is committing genocide against Jews, it doesn’t take long for Sam to identify with Joseph, to believe in his innocence, and to place his entire career and future in hands of Thurgood.

Boseman and Gad have a terrific rapport straight out of a buddy movie. Whereas Thurgood is a dynamic legal mind and a handsome, dashing, room-commanding social presence, the portly and unassuming Sam is a smart but cautious sort when it comes the law, and the kind of fellow who is invisible when HE walks into a restaurant or a party.

It’s the Sam character that gets most of the laugh-inducing and applause-getting “movie moments.” At times Thurgood is little more than a straight man for Sam’s theatrics. (These were not my favorite scenes in the film.) Props to Josh Gad for seizing his spotlight moments without ever overplaying his hand and making Sam a caricature. I loved his work in this film.

Kudos as well to Kate Hudson for her work as Eleanor Strubing, a complicated and deeply troubled character, and we’ll leave it at that. Hudson has the opportunity to play some classic (and somewhat clichéd) courtroom testimony scenes, and she is more than up to the task.

Sterling K. Brown (who played Christopher Darden to great effect in “The People vs. O.J. Simpson) has a couple of outstanding moments as Joseph, who has lived a far from exemplary life but maintains his innocence even when he’s offered favorable plea bargains. James Cromwell is James Cromwell, so of course he delivers as the old-school judge.

But it’s up to Boseman to carry the story, and that he does.

When we think of Thurgood Marshall, I would venture the first images most of us see are of an immensely accomplished elder statesman in a justice’s robe, his visage worthy of a spot on Mount Rushmore. “Marshall” reminds us that before the legend, there was the badass young warrior.

★★★

Open Road Films presents a film directed by Reginald Hudlin and written by Jake Koskoff and Michael Koskoff. Rated PG-13 (for mature thematic content, sexuality, violence and some strong language). Running time: 118 minutes. Opens Friday at local theaters.