John Nash is a brilliant but asocial mathematician fighting schizophrenia. After he accepts secret work in cryptography, his life takes a turn for the nightmarish.

Based on the real life story of legendary cryptanalyst Alan Turing, the film portrays the nail-biting race against time by Turing and his brilliant team of code-breakers at Britain's top-secret Government Code and Cypher School at Bletchley Park, during the darkest days of World War II.