In the wee hours of February 20, 2002, a 27-year-old man named Mark Schluter has a near fatal crash in his truck on a desolate stretch of highway near Kearney, Nebraska. Mark is taken to Good Samaritan Hospital and his older sister and only remaining relative, Karin Schluter, leaves her job to be with him during his recovery. When Mark comes to from a temporarily induced coma due to brain injury, he thinks that Karin is an imposter due to Capgras Syndrome in which a person does not recognize blood relatives after a head injury. Karin sees a mysterious note that was left in his hospital room supposedly from the person who rescued Mark the night of the accident but no one can be identified as the source. Frustrated by Mark's refusal to recognize her, Karin writes to noted neurologist, Gerald Weber, to enlist his help. Karin had always taken care of Mark due to lack of appropriate attention from their religious fanatic mother and lazy father so she leaves her job and home in Sioux City to take care of Mark during his recovery.

Mark slowly heals and is eventually moved to a rehab center where he takes a shine to a nursing assistant named Barbara Gillespie who dedicates time to Mark even after he returns home. Karin, who had been staying in Mark's mobile home, moves in with an old boyfriend named Daniel Riegel, a mild mannered man who is a devotee of protecting the environment for the cranes that return to the area every spring. Mark's paranoia extends to his friends now and he believes that he is being spied on and perhaps his accident was not an accident at all but a means of getting rid of him for some reason. Dr. Weber visits from New York, examines Mark and recommends therapy before quickly returning home. Dr. Weber is having issues of his own with his marriage and the fallout from critics who are not kind to his latest book.

Mark becomes obsessed with finding the author of the note for a clue to what caused his accident and even contacts a television crime show who broadcasts his story. Daniel enlists Karin to work at the crane nature preserve at the same time that she takes up with a former boyfriend, Robert Karsh, who is a town leader and particularly active in growth and expansion enterprises. Karin obsesses over Mark's compromised mental state and writes Dr. Weber, requesting that he return to help Mark. Dr. Weber meets Barbara at Mark's house one day and he is smitten by her, even telling his wife about her when he returns home. Robert Karsh's expansion group wins out over Daniel Riegel's preservationists and Daniel soon surmises that Karin was at the hub of sharing proprietary information about the nature preserve with Karsh so that he has an advantage over how the county land will be used.

Karin entreats Dr. Weber to return one more time to help Mark and this time Dr. Weber has a tryst with Barbara. It is finally Daniel who recognizes Barbara as a news broadcaster who has been posing as a nurse's aide for months to help Mark. It is revealed that Barbara was burned out in her work, went to Nebraska to do a simple story about the cranes and got caught up in the battle between the preservationists and the expansionists. Barbara is finally able to tell Mark that it was she who was out on the desolate road the night of his crash and she had gone to the hospital immediately to see about his condition and it was Mark himself who wrote the mysterious note.