Lourdes is a Spanish woman working behind the scenes at a New York bar and restaurant, clearly with few employment prospects judging by her endurance of the abuse meted out to her by her female employer. As we watch her daily routines, often working into the night after all the guests have departed, we learn that she is in the US to earn enough money for her son's much needed operation back in Spain. We also learn that there are other shadowy presences in the resatuarant, just out of sight of Lourdes as she makes her rounds, which lead her (and us) to think that the place is haunted. Clearly struggling to build up some cash, she accepts the opportunity to increase her savings by going down on one of the diners who is looking for a quick thrill. Disgusted with her predicament, she nevertheless seems to repeat this service for other lone males as it appears lucrative. The shadowy figures become gradually more corporeal however, as Lourdes's predicament becomes ever more desperate.
That's about all I can tell you given the no spoiler policy of this blog. What I can mention is that Lourdes is found dead in the restaurant at the beginning of the movie, making Devoured a 'whydunit' instead of a 'whodunit'. Now the thing about a plot device like this is that the rest of the film has to be strong enough to make you forget the point where you started from, so that when the movie returns to the opening shot there's a renewed surprise and a sense of a satisfying ending. The problem with Devoured is that because the whole film is predicated upon THE TWIST it's presented in both a confusing and mundane way which is uninvolving - something which dogs many of Mr Shyamalan's films - so you never forget that Lourdes ends up dead.
I also found the central character of Lourdes similarly unengaging. Again, this is in service to THE TWIST (OK, I'll stop that now) but as she's in every scene in a film which is already flat and lifeless it made for a pretty tiresome watch. I may be in a minority here - many other reviewers have gone for this in a big way, mainly because of its 'indie' approach, similar to other recent films like The Pact and Lovely Molly. But despite its funky New York setting and some vaguely interesting camerawork, I found Devoured rather shallow and manipulative and not half as good as it obviously thinks it is.