Ava (Jessica Chastain) is a deadly assassin who works for a black ops organization, traveling the globe specializing in high profile hits. When a high profile job goes horribly wrong, Ava's career takes a bad turn. With a botched hit (as well as a track record for talking to her targets before killing them), Ava is told to take a hiatus until the heat blows over, but secretly the head of the organization, Simon (Colin Farrell), has ordered a hit on her to ensure nothing traces back to the company. Her mentor, Duke (John Malkovich), tries to fight for her, but Simon's mind is made up.

Ava decides to go back home to Boston and attempt to mend her relationship with her mother and sister, Judy, though the homecoming proves to be far from happy as the years of estrangement have created resentment. To complicate things further, Ava's ex-fiancé Michael (Common) is bitter that she left eight years earlier and never explained to him the reason for her actions. He's now in a relationship with Judy, and involved with an underground gambling ring that Ava knows all too well from her younger days. Ava now has to save her family and herself from multiple threats, while battling her own demons.