White cat Sable's younger brother Flicker suffered from "stripe extinction"—his tail's ring markings were accelerating toward extinction. Without an exorbitant "life-stripe transplant surgery," he'd be completely erased within 30 days. Desperate, Sable came to the underground black market and signed a life-debt contract: selling her remaining eight lives. The buyer was Onyx, the most feared black cat in the city, an arms dealer and underground emperor who owned half the city. Onyx didn't want her life to extend his own—he wanted a "death-substitute cat." Onyx's enemies tried to assassinate him every day; he needed Sable to test poisons, trigger traps, take bullets for him. Every time she died, one copper ring on her tail went dark, her white fur darkened a shade, and the end of being forgotten by the world drew closer. But through dying and reviving again and again, Sable discovered Onyx hadn't bought her just as a substitute—he was looking for a "cat that can't die" to carry out an impossible mission. And that mission was connected to Sable's missing mother of many years.
