Kingdom of the wicked series book 4
Normally quiet and romantic Emilia is anguished and desperate to not only stop further killings but figure out what happened to Vittoria and avenge her death. Vittoria, the extroverted and bold twin, had been keeping a romance secret, so when Emilia finds her sister's journal of spells, she decides to try them but accidentally summons one of the seven Princes of Hell, also known as the Malvagi or the Wicked: Wrath (they're all named after the Deadly Sins, so the others are Pride, Greed, Lust, Envy, Gluttony, and Sloth). KINGDOM OF THE WICKED by Kerri Maniscalco follows Emilia, a Sicilian witch whose twin Vittoria is brutally murdered, one of several local young women from witchy families to wind up dead.