Joe Darrow (KEVIN COSTNER) is a doctor who's in charge of emergency room operations at Chicago Memorial hospital. When his wife and fellow doctor, Emily (SUSANNA THOMPSON), is accidentally killed while doing volunteer work for the Red Cross in Venezuela, Joe deals with that by throwing himself into his work.
The hospital administrator, Hugh Campbell (JOE MORTON), doesn't think that's a good idea, a sentiment shared by Joe's lawyer neighbor, Miriam Belmont (KATHY BATES), who knows what it's like to lose a loved one.
Nevertheless, Joe puts in long hours, during one of which he has a strange encounter with an unconscious boy, Jeffrey Reardon (ROBERT BAILEY, JR.), who he swears was calling out his name while being wheeled into the ER. Despite having been declared dead, Jeffrey later recounts seeing Joe in the room with him, as well as that of Emily who apparently had a message for Joe. Jeffrey can't recall what it is, but the odd symbols he keeps drawing - something of a squiggly cross - seem to have some connection to all of that.
As Joe tries to figure out what that means, he begins experiencing what appear to be supernatural events in his home, while another child patient, Ben (JACOB SMITH), has also drawn those same symbols and similarly claims to have seen Emily who told him to tell Joe to meet her at the "rainbow."
With everyone believing Joe to be simply experiencing denial or perhaps going crazy, he can't shake the feeling that Emily is trying to contact him from "the other side," a point reaffirmed by Sister Madeline (LINDA HUNT), a nun who previously investigated near death experiences.
From that point on, and as the supernatural events keep occurring, Joe tries to figure out whether he's losing his mind or truly is receiving signals from beyond the grave.