Dahlia (Jennifer Connelly) wants to move away from her ex-husband, Kyle (Dougray Scott), and take her daughter, Ceci (Ariel Gade), with her. Relocating to a dreary tower block, Dahlia and Ceci discover eerie, dark water leaking through the ceiling of their new apartment. Dahlia petitions the supervisor (Pete Postlethwaite) and the building's owner (John C. Reilly) to fix the leak, yet it only gets worse. Now having nightmares about the dripping, Dahlia is driven to confront the problem herself.
