Released from the containment spell trapping her in a diary, Cassia Kallias finds her family embroiled in a war with the egotistical god who spelled her there, but Zeus still covets the power he senses deep within her. As the Demon King, Lucien struggles to contain the chaos spiraling out of control throughout Dark World, but when he accidentally hits the diary of judgments with his demon flame, he releases Cassia from her curse. Reunited with the daughter she was forced to leave, Cassia must come to grips with all she has lost, accept her growing feelings for Lucien, and learn to control her new powers to defeat Zeus to save Dark World and those she loves.