After more than a year of laying low, Billie, Helen, Mary Alice, and Natalie are called back into action. They have enjoyed their rest, but the lack of excitement is starting to a professional killer can only take so many watercolor classes and yoga sessions before she gets the itch to get back in the game. When they receive a call from Naomi Ndiaye, the head of the elite assassin organization known as the Museum, they are ready tackle the greatest challenge of their careers. Someone on the inside has compiled a list of important kills committed by Museum agents, all of them connected to a single, shadowy figure, an Eastern European gangster who rules her business empire with an iron fist and plays puppet master in international affairs. Naomi is convinced this criminal queen is bent upon revenge, killing off the agents who attempted to thwart her, and the aging quartet of killers is next. Together the foursome embark on a wild ride across the globe on the double mission of rooting out the Museum’s mole and hunting down the gangster and her assassin. But their nemesis is unlike any they’ve faced before, and it will take all their experience and a whole lot of luck to get out of this mission alive.