In the middle of the 19th century, linguist James Murray (Mel Gibson) works passionately on his ambitious dream: the creation of the first edition of the Oxford English Dictionary, the most comprehensive dictionary of the English language to date. He is supported by an ominous Dr. William Chester Minor (Sean Penn), who sends Murray 10,000 posts over the years. The researcher has no idea that his passionate supporter ekes out an existence in a high-security psychiatric ward. But between the two disparate men, who are considered "crazy" for completely different reasons, a strong bond develops to create a common legacy: the largest English dictionary of all time! Based on the bestseller of the same name by Simon Winchester and with a large star line-up, THE PROFESSOR AND THE MADMAN tells the fascinating story of two extraordinary men who make the seemingly impossible possible.