Nightbird

Kiera is a nightbird, a thief who flits about the vast city of Velaroth stealing what she can in order to survive. Fiercely independent, Kiera refuses to indenture herself and her two close friends, Wesley and Russel, by joining one of the larger gangs in the city. Wesley is a young man and a pathological liar. His little brother, Russel, is an autistic savant that communicates only through sign but who could secretly be the most powerful techno-arcanist the empire has ever known.
Deep in debt to the underlord Nimat, Kiera dives into evermore dangerous schemes that puts her in opposition to many of the city's most powerful people. But lurking in the shadows is an enemy more deadly and insidious than anyone could imagine, and Kiera and her friends might be the only thing standing between it and a second cataclysm.