Several years after successfully designing a revolutionary high-speed monoplane, famed British aviator R.J. Mitchell (Leslie Howard) travels to early Nazi Germany for a vacation with his friend Geoffrey Crisp (David Niven), a test pilot. There, while watching a group of German gliders, Mitchell realizes that German air technology is rapidly advancing, and that the fate of Britain could hang in the balance. Despite serious illness, Mitchell sets out to develop a new warplane for Britain.