Strangely enough, almost all of the scenes in the "dark forest" take place in bright sunlight. So much for a chance at greater atmosphere.
But the crawlspace is strangely sinister from the start, and as it turns out, is at the centerpiece of the mystery of why the house is haunted.
Nothing much actually happens in the "dark forest" but when the entities enter the house, the fun begins. It's only after a priest has given the house a blessing, that the story takes up any urgency.
The priest's blessing is only a temporary one, pacifying the entities for awhile. But then the couple enlist the aid of a psychic and a priest to get to the cause of further hauntings.
In the crawlspace the psychic is able to see dead bodies and reveals some of the history of the house. It was originally used as an inn for weary travelers. The spirits of these passengers, most of whom were killed or died in the house, are being held there by a stronger presence of a woman who doesn't want them to leave.
Finally, the family decides to move from the house holding multiple entities when it's clear that they cannot overcome the evil within.
Only scary in the second part when suspense finally builds. Pretty slow going before that but good acting makes it compelling enough.