Over Thanksgiving weekend, all but five students in an old Manhattan building that's now a college dormitory leave for home: staying on one floor are roommates Lauren, Melina, and Alison, plus her boyfriend Diego and Grant, a loner in a room down the hall. Lauren's been seeing things in her bathroom: a silent child of about six. Diego has written a paper on parapsychology, so he holds a séance with the disbelieving co-eds. Something goes awry, because bad things start to happen and the students' only defender is an aging campus cop named Syd. What's the silent ghostly girl's secret, and can Alison discover what's going on before it's too late?

Thanks to an auto accident, a parasitic alien manages to get into a hospital. It quickly moves from the crash victim into a candy striper. Among the patients at the hospital are some rather short high school basketball players. It is through them that we watch the events unfold. The infected, or inhabited, candy striper becomes predatory. She goes after men for sex and after women to spread. Infected women develop an incredible sweet tooth and devour anything sweet they can find. The horror then spreads. As the horror takes over more of the hospital and the CDC locks it down, the basketball players and a few friends do everything they can to try and get out of the hospital. But soon it becomes evident that the problem has spread too far. Now if they manage to escape it will only be to delay the inevitable if they cannot halt the spread of aliens before they get out and take over the whole world.