In the tumultuous year of 1934, after evading capture for two long years as notorious robbers and murderers, the infamous couple Bonnie (Emily Brobst) and Clyde (Edward Bossert) orchestrate a daring escape, breaking several of their associates out of the Eastham Prison Farm in Texas. In reaction to this bold move, Lee Simmons (John Carroll Lynch), the Chief of the Texas Department of Corrections, convinces Governor "Ma" Ferguson (Kathy Bates) to recruit the seasoned former Texas Ranger Frank Hamer (Kevin Costner) to independently track down the duo, bypassing the involvement of the FBI.
Initially, Ferguson and her team express doubts about Hamer's capabilities, having dismissed the Rangers for more modern law enforcement units. However, she reluctantly permits Simmons to proceed with the hunt. While Hamer grapples with the weighty decision due to his family ties, both he and his wife Gladys Hamer (Kim Dickens) realize they cannot ignore the chilling reports of a violent shootout in Missouri connected to the infamous pair. Desperate for action, Hamer's former partner, Maney Gault (Woody Harrelson), joins him, motivated by a long spell of unemployment and hardship.
As the story unfolds, the FBI has already been monitoring the families of the fugitives through wiretaps. Hamer and Gault gain access to these crucial files, leading them to suspect that Bonnie and Clyde are making their way towards Dallas. During their search, they witness a disrespectful act— a man hurling a bottle at Bonnie's mother's house— and give chase to a young boy who flees the scene. The FBI, already on the case, advises the Rangers to steer clear, suggesting that Clyde is currently in Brownsville. Disregarding the FBI's warnings, the Rangers reach out to Dallas Sheriff "Smoot" Schmid, who introduces them to Deputy Ted Hinton (Thomas Mann), a childhood acquaintance of the criminals who can recognize them instantly, though previous hesitations about confronting them raise concern among Hamer and Gault.
The plot thickens when they hear of a double police homicide linked to Bonnie and Clyde near Grapevine. As they investigate the aftermath with Hinton, Hamer is horrified by the sheer brutality displayed by the notorious pair, noting particularly that Bonnie has a strange fondness for a white rabbit, believed to be a gift for a loved one. Leaving Hinton behind, their pursuit leads them to Oklahoma, where they learn from a sympathetic gas station attendant that they are headed toward a migrant camp.
Continuing their relentless chase, the Rangers encounter further tragedy as they learn about two more slain officers on their radio during their search for Bonnie and Clyde. When they travel to Coffeyville, Kansas, anticipating the gang's need for supplies, they finally catch a glimpse of Bonnie and Clyde but are momentarily thwarted by a cheering crowd. Despite this, they manage to fire shots at the fleeing duo, but their quarry escapes yet again.
In a desperate bid to retrace their footsteps, Hamer uncovers that Clyde recently had breakfast in Amarillo and gets word that Bonnie's family received a delivery intended for her. A poignant meeting unfolds with Clyde's father, Henry Barrow (William Sadler), who sorrowfully asks Hamer to "end it," fully aware that his son would never surrender alive. Implementing a plan that involves furloughing a prisoner associated with the gang, Hamer seeks to lure Bonnie and Clyde into a trap. Their investigation takes a dark turn when they discover the body of their informant, Wade McNabb, brutally murdered.
Feeling responsible for McNabb’s death, Gault is deeply troubled, but Hamer reassures him as they carry on. By analyzing their adversaries’ patterns, they deduce that “criminals always go home,” leading them to believe the gang would return to Louisiana, specifically the home of gang member Ivy Methvin (W. Earl Brown). As they arrive at Methvin’s residence to gather evidence, they garner support from local sheriffs after confirming their integrity, leading to an impending showdown.
That night, Gault shares a haunting story from his past deployment which resulted in the tragic death of a young boy, deepening their bond. With Ivy's cooperation, the posse organizes an ambush, using Ivy's broken-down vehicle as bait. When Bonnie and Clyde arrive to render assistance, Hamer makes his move, commanding them to surrender. As they prepare to fight back, tragedy strikes—the posse opens fire, swiftly eliminating the infamous couple before they can react.
The aftermath reveals a scene of chaos with the bullets-riddled car and the lifeless bodies of Bonnie and Clyde being paraded through Arcadia, Louisiana, amidst a frenzy of onlookers. Declining a lucrative offer for an interview related to their triumph, Hamer and Gault silently make their way homeward, left to reflect on the legacy of two lives lost, as thousands gather to pay their respects at Bonnie and Clyde's funerals.
