Singapore, 1972: Newly independent and grappling for power in a fast-modernizing world. Here, gangsters in Chinese secret societies are the last conduits of their ancestors' migrant gods, and the back alleys where they fight are the last place magic has not been assimilated and legislated away.

Loner schoolgirl Adeline Siow has never needed more company than the flame she can summon at her fingertips. But when her mother dies in a house fire with a butterfly seared onto her skin and Adeline hunts down a girl she saw in a back-alley barfight—a girl with a butterfly tattoo—she discovers she’s far from alone.

Ang Tian is a Red Butterfly: one of a gang of girls who came from nothing, sworn to a fire goddess and empowered to wreak vengeance on the men that abuse and underestimate them. Adeline’s mother led a double life as their elusive patron, Madam Butterfly. Now that she’s dead, Adeline’s bloodline is the sole thing sustaining the goddess. Between her search for her mother’s killer and the gang’s succession crisis, Adeline becomes quickly entangled with the girls’ dangerous world, and even more so with the charismatic Tian.

But no home lasts long around here. Ambitious and paranoid neighbor gangs hunt at the edges of Butterfly territory, and bodies are turning up in the red light district suffused with a strange new magic. Adeline may have found her place for once, but with the streets changing by the day, it may take everything she is to keep it.