A man wearing sunglasses and calling himself Plot (Kevin Spacey) suddenly appears at Central Park Station in New York. He claims to be from K-PAX, a star a thousand light years away from Earth near the Lyra constellation, and came to Earth for investigation at superluminal speed. Plot is admitted to Manhattan Mental Hospital as a mental patient and is treated by Dr. Mark Powell (Jeff Bridges). Mark thinks Plot is a patient with delusions, but he is skeptical about Plot's strange behavior and incredible astronomical knowledge. At the same time, Plot's arrival caused a sensation among other patients in the hospital, and everyone hoped to be selected to follow Plot back to K-PAX. Dr. Mark tried his best to find out Plot's true identity, but he didn't expect that he would be more and more convinced by Plot's theory in the process. What is Plot's true identity? The film was nominated for the Best Actor (Kevin Spacey) by the American Science Fiction, Fantasy and Horror Film Association.