Six of Crows
By Leigh Bardugo. In this young adult fantasy novel, set in a cosmopolitan and mercenary city-state modeled on 19th-century Amsterdam, a crew of six thieves and underworld denizens must break into an impenetrable fortress to rescue the inventor of a magical weapon that could spark a devastating war. The world-building, social conscience, diversity of characters, and twist-filled plot are all outstanding. The story continues in the sequel Crooked Kingdom.