For a while, this atmospheric British period ghost story was feeling more like 4 stars, but a pretty sloppy final act slightly undermined the overall impact.
Rebecca Hall plays an author and semi-famous ghost hunter in the period just after WW I. A Cambridge educated atheist, she specializes in dispelling ghost hoaxes. Guess what the plot of the movie is, based on that setup!
The early scenes play a bit like a Holmes story--Dominic West shows up to hire her to investigate a ghastly mystery at the boarding school he teaches at, so she ends up combing the grounds of the Downtown Abbey-esque school for clues as to who's putting on the hoax.
Meanwhile, we start to get hints that Hall, West, and most of the other main characters are all dealing with their own personal demons of various kinds, mostly involving guilt and isolation. Surivor's guilt, in particular, is a main focus, as many of the male characters are seemingly psychologically crippled as a result of the war.
So the first 2/3 of the movie is pretty excellent. There are some genuine hair-tingling chills in the vein of The Others (a move that pretty obviously inspired this inferior homage), and Hall and West are very good. The cinematography is also really excellent--the big old house is used to good effect with all sorts of passageways, peep holes, and creaking staircases.
Still, the movie does seem to lose its way over the last half hour or so--there's a tonal change, and then a sort of lame and unsatisfying (not to mention convoluted) big reveal. I wouldn't skip it on that account, though. I could well imagine others feeling less annoyed by the end, and this one definitely has some game.