When petty thief Sal Leon steals a poster from a royal scribe announcing open auditions for The Left Hand, Sal knows it's a chance for a better life. The Queen's powerful personal assassins are named after the rings she wears—Ruby, Emerald, Amethyst, and Opal—and are her most trusted advisors.

But the audition is a fight to the death filled with clever circus acrobats, lethal apothecaries, and vicious ex-soldiers. A childhood as a common criminal hardly qualifies as preparation, but with each success, Sal comes closer to victory…and to the nobles who destroyed everything. Because Sal is there not only to win—but to get revenge.