Joe (Joaquin Phoenix, Her, Inherent Vice) is a hired gun who rescues trafficked girls, using brutal methods against those responsible. Caring for his elderly mother in his childhood home in New York City, he suffers from graphic flashbacks of his childhood, the abuse he and his mother faced from his violent father, and the brutal past in the military and FBI, and has suicidal thoughts.

He embarks on a blood-drenched rescue mission, when Nina (Ekaterina Samsonov), the innocent 13-year-old daughter of an ambitious New York senator, never returns home. But amidst half-baked leads and a desperate desire to shake off the heavy burden of a personal hell, Joe's frenzied plummet into the depths of Tartarus is inevitable, and every step Joe takes to flee the pain, brings him closer to the horrors of insanity.