Forty years after an unfinished occult ritual resulted in the disappearance of six kids, an American family has moved into a never before inhabited house in Spain. The mother, Maria (LENA OLIN), wants to get the place in order, while the dad, Mark (IAIN GLEN), goes to work, and their kids, teenager Regina (ANNA PAQUIN) and her younger brother Paul (STEPHAN ENQUIST), try to settle into their daily routines.
It helps that Mark's doctor father, Albert Rua (GIANCARLO GIANNINI), is nearby, especially when Mark begins to suffer from some mental breakdown attacks that periodically reoccur. Regina is not only worried about him, but also Paul who's now scared of the dark for the first time. The young boy has reason for that, however, as there seems to be some sort of supernatural force beneath his bed. We also occasionally see supernatural figures of what appear to be kids standing in the shadows and darkness, watching the family.
As Paul becomes more scared and their father increasingly unstable, Regina eventually figures out it must have something to do with their home where the power is lost everyday. With the help of her new friend, Carlos (FELE MARTINEZ), the two eventually meet the man, Villalobos (FERMIN REIXACH), who designed the house, and learn that it was built for supernatural reasons to coincide with an eclipse that only occurs every forty years. With the next one quickly approaching, and now armed with the knowledge that the earlier occult ritual needs one more death to be completed, Regina races to make sure that Paul isn't the final victim.