In the heart of Mexico City, a young boy named Fenix grows up in a circus amongst a colorful yet dysfunctional family. His father, Orgo, is a knife-thrower and cult leader, while his mother, Concha, is a religious zealot who worships a deity of her own making, the armless figure of Santa Sangre. Fenix's childhood intertwines with performance, religion, and bizarre spectacle; these elements shape his world in a traumatic tapestry. Tragedy strikes during a heated argument when Orgo viciously mutilates Concha, cutting off her arms, before he takes his own life in front of Fenix, leaving the boy distraught and doomed to a mental institution.

Years pass, and an adolescent Fenix escapes the mental facility, only to be dominated by his armless mother who persuades him to become her arms, performing on streets and eventually rejoining the showbiz world. This intimate, unholy alliance drives Fenix deeper into a psychological abyss as he becomes an extension of his mother's unfulfilled desires and vengeances. The lines blur between performance and reality, leaving Fenix caught in a twisted battle between his own budding individuality and the overpowering maternal bond that refuses to release him.