Kingdom of the Wicked (Kingdom of the Wicked, 1) by Kerri Maniscalco

Kingdom of the Wicked is a dark fantasy novel that follows Emilia, a young witch living in 19th-century Sicily. When her twin sister, Vittoria, is brutally murdered, Emilia vows to find the killer and seek revenge. Her search leads her into the dark and dangerous world of the Wicked—demonic princes who are forbidden to interfere with the mortal realm. Emilia inadvertently summons Wrath, one of the seven demon princes, and the two form an uneasy alliance to uncover the truth behind her sister’s death. As they delve deeper into the mystery, Emilia finds herself entangled in a sinister plot that could destroy everything she holds dear.