Serenity is just your average college girl, but when she suddenly loses contact with her father Dr. Aleister, she sets out to find him at the Salem State Hospital & Asylum where he works. Serenity arrives to finds she barely recognizes the hospital anymore. Stepping warily into the shattered ruins, she meets a talking teddy bear. Introducing himself as David, the talking teddy bear claims to have once been human, but when Serenity asks him about her father’s whereabouts, countless demons suddenly appear. Just before her father disappeared, he had sent a mysterious app to her smartphone. Known as the Demons' Score, the app is a powerful program that enables her to take control of demons that possess her body. Where has her father gone? How will she ever find him? And what’s up with that talking teddy bear? Serenity’s battle to the tune of Hell’s minions is about to begin.