A mysterious woman in a red dress blesses herself outside a church where a wedding is in full swing. She walks down the aisle. BANG! BANG! BANG! She shoots the bride dead in front of the horrified guests. The lady in red speeds off amidst a hail of gunfire unleashed by some of those attending the wedding. Molly Parker (Tricia Helfer), one of the first women to join the elite group of law enforcement agents known as the Texas Rangers, ditches her beauty parlor appointment to join in the police pursuit. She runs the getaway car off the road and draws her rifle. When the car door opens, a short, bearded man steps out. The lady in red is gone.
The murdered bride was an assistant district attorney. The groom claims he doesn't recognize the shooter even though she works at one his gyms. The suspect, Martina Alvarez, called the guy nine times just before the wedding. Molly works with the San Antonio police department to capture the suspect at a local motel. She doesn't quite buy the arrogant Lieutenant Guillermo Salazar's theory that this shooting was a crime of passion. After all, Martina Alvarez's nails were chipped. Molly tells her boss, Lieutenant Luis Zea (Alex Fernandez), that you don't shoot the wife of your soul mate without looking like the one he should have picked.
Molly has been staying with the family of her brother, Billy Parker (Michael Trucco), a former Special Forces soldier. Her sister-in-law, Becca, is more like a best friend. Her ex, Senator Jake Colton, lets her know he's moved out of their loft even though he vows to never divorce her. As for the case, Molly digs deeper into the wedding shooting. She asks DEA agent Dan Winston (Marc Blucas) why the ADA was meeting with him. The guy is busy on a bust, so Molly moves on to question Martina. Her instincts tell her that there's more to her story.
Molly gets a flirty text from DEA Dan which leads to a bedroom interlude. While basking in the afterglow, she seeks information on the Alvarez case. Dan isn't willing spill any details, but Molly believes Martina is working for the cartel. It's not a theory anyone else shares. This makes Molly a bit of a lone ranger. She learns that Martina Alvarez has a daughter just before the suspect is shanked in the shower. It's not a fatal blow. Molly suspects Martina's mother and daughter have been kidnapped by the cartel. She tells Martina how her ex-husband beat her. She felt ashamed and trapped. She promises to find Martina's family.
Molly lets Dan know that Martina is willing to testify against the cartel. The DEA and DA's office were working together on a case that involved transportation in $40 million in contraband annually. Molly wants Dan's help to get Martina's family away from the cartel and out of Mexico. They need to do this alone. There's an excellent chance they won't get out of it alive. They track down Martina's family, but the cartel returns before they can make a clean getaway. A perilous gunfight ensues. As Ben speeds off, Molly shoots a container that explodes assuring their escape. A short time later, Martina is reunited with her family.
With the case closed, Molly marches into her ex's office. She orders him to sign the divorce papers or she'll tell the world what a monster he truly is. At the office, Lieutenant Zea lets Molly know that if he ever finds out she crossed the border to free Martina Alvarez's family, he'll fire her. He'll do this in spite of their relationship, which is revealed to others only on a need-to-know basis. A short time later, Molly is surprised to see Dan show up at the bar where she plays trumpet with the band. This is one Texas Ranger wears more than just one cowboy hat.