Dr. Geoffrey Fuller, a well known psychiatrist heads the Psychiatric Centre in Boston. He and his wife Elizabeth, who is a radio talk show host in Boston, live in a seaside home south of the city. During one of his daily walks on the beach, he discovers a diary whose owner he cannot identify. Although he is quite busy managing his psychiatric center in the city, especially with a young patient who has somehow lost his ability to speak, and with whom Dr. Fuller has developed a special interest and concern, he is fascinated by the contents of the diary which he has perused in an attempt to discover its author. Through this discovery process the diary seems to harbor a mysterious secret with which he and Elizabeth progressively become entangled and find themselves helplessly drawn into unraveling its secret.