Don't mistake "Till," now blazing its truth in theaters, for homework or eating your vegetables. That happens a lot when a real-life tragedy -- in this case the 1955 lynching of 14-year-old Emmett Till for the crime of being Black in Mississippi -- becomes an excuse for Hollywood to bury vital issues, such as civil rights, under the stultifying banner of prestige filmmaking.

Not this time.

"Till" is an emotional powerhouse that goes its own defiant way as the intimate and indelible personal journey of an activist mother who honors her murdered son by showing how his life and brutal death helped galvanize the civil rights movement.

All praise to Nigerian-American director and co-writer Chinonye Chukwu, 37, best known for 2019's "Clemency," in which Alfre Woodard dug deep as a prison warden at odds with capital punishment.

PHOTO: Jalyn Hall as Emmett Till in "Till."
Andre D. Wagner/Orion Pictures
Jalyn Hall as Emmett Till in "Till."

Did it take a woman to film this raw and riveting tale of a mother's love? It took two women, actually. Sharing Chukwu's triumph is Danielle Deadwyler, who is nothing short of stupendous as Mamie Till, a Chicago widow who's feeling anxious about putting her son Emmett (a sweet, spirited Jalyn Hall) on a train to Mississippi to visit the family of his sharecropper uncle Moses (John Douglas Thompson).

"Be small down there," she warns him.

PHOTO: Danielle Deadwyler, as Mamie Till Mobley, left, and Jalyn Hall, as Emmett Till, in "Till."
Orion Pictures
Danielle Deadwyler, as Mamie Till Mobley, left, and Jalyn Hall, as Emmett Till, in "Till."

It's Mamie's mother, Alma -- producer Whoopi Goldberg in a stunning cameo -- who insists that Emmett needs to know where he comes from, a hard lesson in white supremacy he learns all too well.

The devastating result is Emmett's battered, bloated, disfigured body being pulled out of the Tallahatchie River and returned to Chicago for burial. Mamie refuses a closed casket, insisting, "The whole world has to see what happened to my son."

Given Mamie's plea for full disclosure, some have criticized Chukwu for refusing to depict the savage brutality inflicted on Emmett. We see only the prelude to his murder as Emmett whistles at Carolyn Bryant (Haley Bennett), a white grocery clerk whose false accusations of sexual misconduct led her husband and brother-in-law to kidnap Emmett and kill him.

During Mamie's testimony at the Mississippi trial of Roy Bryant and his half-brother John William "J. W." Milam, the camera holds on Deadwyler's face as Mamie realizes there's no way in hell this all-white, all-male jury will convict her son's killers. Still, out of that despair, a lifelong activist is born.

Deadwyler, so good in "The Harder They Fall" and "Station Eleven," plays Mamie like a gathering storm. When the NAACP hires her to go on fundraising tours, she is told to hide her relationship with future husband Gene Mobley (Sean Patrick Thomas), the better to pass as the saint she never pretended to be.

PHOTO: Sean Patrick Thomas, as Gene Mobley, left, and Danielle Deadwyler, as Mamie Till Mobley, in "Till."
Lynsey Weatherspoon/Orion Pictures
Sean Patrick Thomas, as Gene Mobley, left, and Danielle Deadwyler, as Mamie Till Mobley, in "Till."

Mamie knows the risks. The example of civil rights leader and future martyr Medgar Evers (Tosin Cole) is harrowingly close. And yet she fights on. Deadwyler gives the role a no-bull authenticity that merits all the raves she's been receiving as the breakthrough star of the year.

Deadwyler is too good to let a movie turn Black trauma into cheesy Oscar bait. Even when the film lets conventional biopic tropes mess with momentum, Deadwyler never loses her uncanny connection to the female warrior she's playing.

Mamie died at 81 in 2003. She is buried near her son, where her gravestone reads, "Her pain united a nation." In a galling irony, it wasn't until March of this year, nearly seven decades after Emmett's murder, that Congress passed the Emmett Till Anti-lynching Act.

"Till" snaps with a timely and scary relevance that makes Mamie's battle for justice as urgent as ever.

"Till" is more than a movie -- it's essential viewing.