Complex sentence: However, Max made a deal with the devil in order to return from the grave to frame Lucas for a series of grisly murders and scare the McCarthy family (who have moved into a new house) and the parapsychologist they hire.
Split into simpler sentences: However, Max has made a deal with the devil in order to return from the grave and frame Lucas for a series of grisly murders. He also scares the McCarthy family (who have moved into a new house) and the parapsychologist they hire.