The Zander family run a psychic business bilking people with fabricated seances and readings. They are down on their luck, having lost the man of the house. Its the 60s so that made things all the more difficult. One of the daughters brings a Ouija board back to the house and things go awry, as the youngest daughter becomes the conduit for dark forces.
In most movies, like the first, the dark spirits would be just that -- bad people who died but are still doing bad things. Or good people who died horrible deaths and are vengeful. But this one finds darker things drawn to a house where dark things had been done. Its not just the spirits of the dead, but worse things that were never people to begin with. We are given a world to think about, to ponder, while we are given the requisite jump scares.