Plot

While fleeing from dangerous assailants, an assassin comes out of hiding to protect the daughter she left earlier in life.

A female assassin/operative in the US Army must reluctantly hand over her teenage daughter Zoe to foster parents for safety because of her risky, uncertain duties. Later, certain situations develop in which Zoe is in danger from assassins. The mother takes charge of her daughter and teaches her survival skills while doing everything possible to safeguard her from harm.—Madan Marwah

An unnamed U.S. military operative, known as "the Mother" (Jennifer Lopez), brokers an arms smuggling deal between ex-SAS Captain Adrian Lovell (Joseph Fiennes) and arms dealer Hector Álvarez (Gael García Bernal). Romantically involved with them both, she ends up becoming pregnant. After discovering that they are involved with child trafficking, the Mother approaches the FBI to be an informant.

While the Mother is being interrogated at a safe house by FBI Special agent William Cruise (Omari Hardwick), Lovell attacks the property; Cruise is shot and wounded, and the other FBI agents are killed. The Mother saves Cruise's life and crafts a time-delayed bomb. Lovell confronts her in the bathroom and stabs her before getting knocked out by the explosion. After the ordeal, the Mother gives birth to a girl prematurely in the hospital.

SAIC Eleanor Williams (Edie Falco) informs the Mother that Lovell's body was missing and that her new born daughter will be placed with a foster family for protection. Eleanor says that Lovell stabbed Mother's pregnant belly and so it is reasonable to assume that if he finds out about the daughter, he will come after her. Mother had back-to-back tours in Iraq and Afghanistan. 46 confirmed kills and accurate to 1300 m with an M24. Understanding that the child will never be safe with her, she reluctantly waives parental rights. The Mother visits Cruise, giving him three conditions: the child will have a life as ordinary as possible, she'll get a photo every birthday, and to call her if she is in jeopardy. Mother saved Cruise's life, so he agrees. The Mother then secludes herself in a remote cabin in Alaska for the next twelve years, until Cruise contacts her to meet in Ohio.

Cruise informs her that when the ATF busted some of Álvarez's men in Mexico, they found a photo of her daughter, Zoe (Lucy Paez), suggesting they're onto The Mother. While Cruise and the Mother are shadowing Zoe playing at a park, Álvarez's men kidnap Zoe. The Mother manages to gun down several of them before escaping the cops with Cruise. While he thinks Zoe's kidnapping is for ransom, she knows it was done to lure her out of hiding. She had identified the man leading the kidnapping to be Alvarez's top lieutenant, the Tarantula.

They head to Havana, Cuba in hopes of uncovering a clue to Zoe's whereabouts. They catch Tarantula (Jesse Garcia), Álvarez's lieutenant, who reveals that she is being held at Álvarez's house on "the Plantation". Tarantula says that Alvarez will do unspeakable things to Zoe, and is not likely to make an exchange with Mother for Zoe. Mother kills Tarantula after torturing him.

That night Mother reveals to Cruise that Lovell was ex-SAS training her sniper unit in Afghanistan. Lovell recruited her for covert, off the books operations as she had no family and no future. After that Mother did a tour in Guantanamo bay, where she saw Alvarez siphon guns off the base under everyone's noses. Mother brought Alvarez and Lovell together. Alvarez had the weapons and Lovell had the network to sell them and distribute them. She got into a relationship with both. Mother discovers that Alvarez and Lovell were trafficking children.

Infiltrating his home, together, they rescue Zoe. The Mother then kills Álvarez. Alvarez wanted to know if Zoe was his daughter, but Mother is clear that it doesn't matter.

While escorting Zoe back home, the Mother's gaze upon her makes Zoe realize that she is her biological mother. The Mother decides to part ways and let Cruise return her to her foster parents. Lovell manages to intercept them. The Mother arrives, attacks Lovell and escapes with Zoe. Angered, Lovell kills Cruise.

Realizing Zoe is not safe if she returns home, the Mother takes her to the cabin. Mother calls Zoe's foster parents and informs them that Zoe is safe, but cannot return to her normal life just yet. Mother promises to return Zoe to them, safe. Over time, she teaches the reluctant girl survival training. Mother teaches Zoe how to drive, run, shoot, identifying danger signs in nature and so on. Zoe is angry that Mother still won't admit that she is Zoe birth mother. Mother explains that Zoe has to learn to protect herself.

Zoe is bit by wolf pups in the wild. Mother takes her to the hospital, but Zoe gives out her real name by mistake, which is input into the computer. Mother realizes Lovell is coming for them, she decides to leave Zoe with Jons (Paul Raci), her former army colleague. Upset to know she's being abandoned again by her own mother, Zoe is confronted by Jons, who encourages her to see the Mother through her actions and not her words. After she finds a letter from the Mother, explaining everything she has ever done has been for her, Zoe decides to go back to the cabin and help her ward off the attackers.

Lovell and his men have a final confrontation with the two. The Mother had mined the woods around the cabin. But Lovell finds the mines and uses the mines to destroy the cabin. Lovell's men see Zoe driving up to the cabin and Lovell goes for her. The Mother manages to kill all of Lovell's men before facing him. Zoe was at a vantage point and Mother had told her to run, but Zoe decides to fight instead. She shoots Lovell through Mother's shoulder, proving that she is now as ruthless as Mother is. While Mother is knocked out, Lovell grabs Zoe and speeds away, but the Mother snipes and kills him. With her former allies dead, the Mother returns Zoe to her adoptive family. No longer needing to remain in hiding, she continues to observe Zoe from a distance.