Zen, a young autistic girl, grows up next to a Muay Thai boxing studio and is raised on a steady diet of chocolate and marathon viewings of Tony Jaa and Bruce Lee films. Zen’s father, a Japanese gangster, has been driven out of the country by a rival Thai gang, so her mother has been forced to raise her alone. It becomes clear over time that Zen has miraculously absorbed formidable Muay Thai techniques from watching the boxers next door and repeated viewings of martial arts classics. When Zen’s mother is diagnosed with cancer and the cost of treatments prove overwhelming for the family, Zen sets out with her cousin on a violent mission to collect debts from the corrupt gangsters that owe her mother money.