In a desert cantina, Carli Vincenzo, a lovely woman not yet 35, picks up a ratty biker named Grady, drugs him, stakes him to the ground in the middle of the desert, and shows him a video of him raping her daughter, Lara, then leaves him to be eaten alive by ants and buzzards. When his body is found, the county sheriff, Anson, learns his death is connected to the death of Stasi, a woman who worked with a biker/drug gang in his county.
The gang is led by Dax, a drug kingpin who owns the cantina. An ex-Marine named Zeke, who lost part of a leg, tends bar there. Carli snuck a bug into the bar so learns Anson is in league with Dax.
After closing, Zeke goes to his shack behind the cantina to release his dog, Loki, from its chain. He can't sleep so plays his guitar on the porch as the dog runs about...then stops. Carli appears from the shadows but can't get too close thanks to Loki. She and Zeke talk, they seem to connect, and she realizes he was not one of the rapists.
The next day, two of Dax's men meet a college student/dealer. The student leaves and Carli shoots both men, wounding them, but one is still able to fight her. She kills him then kills the other one the same way as Grady.
She cleans off the blood, calls her mother to find out who the college student is, then watches a video of Lara sending a Christmas greeting...and weeps.
She returns to the cantina. Zeke senses her turmoil so takes her into the desert to watch the sun come up and talk. He thinks she has PTSD.
The next day, Carli interrogates the college student, Chase, and learns Stasi set Lara up to be raped as payment for a drug debt. Zeke tried to stop it but was beaten. Chase had an ear cut off by Dax for interfering.
Anson finds Carli and accuses her of the deaths but cannot prove it. She goes to Zeke but cannot talk. He's figured out she was Lara's mother and feels guilty for not stopping the rape.
They wind up in bed. Carli opens up. She had Lara at an early age, and left the girl to be raised by her own mother. Carli joined the Army and remained out of her daughter's life until the girl was raped. And the video was posted on her college website. And she overdosed on pills. Now Carli's guilt over being an absentee mother gnaws at her.
Zeke was disowned by his family when he went to prison. He joined the marines to get out and was hit by an IED, losing his leg. Dax gave him a place to stay, but he doesn't like the desert. Carli asks him to leave with her. He agrees.
When the next two bodies are found, Dax kills members of another gang, thinking they're the killers. That brings in the State Police and FBI. Anson is furious.
Zeke overhears Anson and Dax discuss Carli and realizes she has killed his friends. He calls to beg her to tell him it's not true, but she owns up to it. Anson and Dax overhear him and try to force him to tell them where Carli is hiding. He refuses and is brutalized.
Carli overhears them, thanks to the bug, and roars in to face them in a battle to the death...one neither she nor Zeke may survive.