Let’s admit the truth, the whole truth and nothing but the truth: We hear there’s a movie about Thurgood Marshall — the crusading civil rights lawyer who argued the landmark Brown v. Board of Education case and became the first black justice on the U.S. Supreme Court — and we expect something high-minded, noble, earnest and medicinal. With heroic music. And halos.

When it opens Friday, “Marshall” may force a reordering of our expectations.

“People are responding to this movie like it’s ‘Wonder Woman,’ “ said Josh Gad (“Book of Mormon,” “Beauty and the Beast”), who plays Sam Friedman, the real-life lawyer who is dragooned by Thurgood Marshall (Chadwick Boseman) into fighting a case of racial injustice in 1941 Connecticut. Gad may not be an impartial witness, but he put his finger on what distinguishes “Marshall” from your standard Hollywood biopic: If they called it “Thurgood Marshall, Superhero” it wouldn’t be that far off.

“At its core, it’s a crowd pleaser,” said Gad. “That might be something with some negative connotations, but I think it’s also hopeful, and empowering. And let’s not forget that Reggie comes from the world of writing comic books, including ‘Black Panther.’ “

“Reggie” is director Reginald Hudlin, whose eclectic career — which began with the comedy “House Party” (1990), directed with his brother Warrington — has indeed included work in the Marvel Universe. And he freely admits the connection.

“Sometimes,” he said, “to appreciate the achievements of these great men we have to take them off the pedestal. In the case of Thurgood Marshall, our mental image of him is as an old man, in robes, sequestered away in the Supreme Court. So to see him as a young man, smoking, drinking, flirting, fighting — you’ll be, ‘Oh I know this guy!’ And when he’s a guy with all this swagger and is the smartest guy in any room he’s in, it’s kind of amazing he’s human. In fact, he’s more than human. So we get back to the superhero place in a very natural, earned way.”

Marshall is played by Boseman, who has had some experience playing trailblazers (Jackie Robinson in “42”; James Brown in “Get on Up”). When the film opens, Marshall is the NAACP’s chief legal counsel and Boseman makes him a charismatic, cocksure crusader for equal rights, one with an unconcealed contempt for institutional racism. Outside of a tender, often long-distance relationship with his beloved wife, Buster (Keesha Sharp), Marshall’s life is dedicated to cases of racial injustice, one of which he finds in Bridgeport, Connecticut — a black chauffeur named Joseph Spell (Sterling K. Brown) has been accused of assaulting and attempting to murder his white employer (Kate Hudson).

The whole case smells, as do the rulings from the bench: Marshall is barred from participating by the presiding judge (James Cromwell). So while Marshall continues to direct the defense, local attorney Friedman has to take over the courtroom presentation.

“The film is pretty close to what actually happened,” said Gad. “It’s a case that’s sort of been forgotten in light of what else happened in the man’s life, but at the time it was tabloid fodder: You had an African-American chauffeur accused of raping his white employer. You had families all over Bridgeport firing any employees who were ‘colored.’ In many ways at that time it was a death penalty to lose your job, so it isn’t just about Joseph Spell. It’s about an entire community.”

It’s also a lot about Friedman, who for director Hudlin represents something more than just a character in an obscure criminal case.

“He’s kind of the audience,” the director said. “We’re all living our lives, getting along, things are unfair but we really can’t complain. And then Thurgood Marshall crashes in — and you realize he’s providing something you’re missing, which is a mission.”

The mission of the film, Hudlin said, has changed a bit since they were making it more than a year ago; race relations weren’t so fraught and the U.S. election was just underway. “Dan Stevens, who’s English, was following the Brexit vote,” he said, referring to the ex-”Downton Abbey” actor who plays prosecutor Lorin Willis. “And we’re saying, ‘Nah that will never happen.’ Then it does and we say, ‘What does that mean?’ And we find out later.

“So the movie does two things,” Hudlin continued. “There’s a comfort that comes from knowing that when good people come together, dedicated to the truth, the truth will set you free.” At the same time, he said, the movie ends with more people coming to Thurgood Marshall for help, with more tales of racial injustice, “and audiences are like ‘Right: The struggle continues.’ And we have to keep fighting. The truth is, freedom ain’t free. And every generation has to be tested.”