Once again a family takes up residence in an isolated country house, and the family dog in particular is against the idea from the start. There are minor oddities, then bigger weirdnesses, then graver and graver threats, as if the spooks used to work in a billing department.
Haunted house movies almost have to follow a formula along these lines, and as with higher forms of art (the sonnet, say), whether the constraints act as limits or as a supporting structure depends on the level of creativity.
The Conjuring, especially the first hour or so, is actually pretty good, managing some original scares and eeriness. If you’re a fan of genre you’ll probably enjoy at least that part, though later on it turns more violent than spooky as the focus increasingly shifts to a pair of married ghost hunters who are trying to help the family.
The film claims to be based on real people and real events as recorded by said ghost-hunting couple and by members of the haunted family. The latter allegedly suffered the hauntings for more than 10 years, far longer than in the film, before finally landing a book contract.