Still re-used the basic idea like previous movies: someone found the Book of the Dead/Naturom Demonto/whatever the name is and accidentically read the incantations, thus some demons are summoned. Hell is unleashed, and eventually they figure out how to beat the demon. Hooraayyy. Unfortunately, they don’t destroy the damn book.
I suddenly remember a famous quote:
Those who don’t know history are destined to repeat it