In 1917 the British poet Siegfried Sassoon writes a statement against the war that is read in Parliament. Faced with the choice of either a court-martial or time in a mental hospital as a result, Sassoon chooses the hospital, and is sent to Craiglockart, a Scottish castle where shell-shocked vets are being treated by Freudian therapist Dr. William Rivers. Sassoon soon befriends a pair of fellow inmates. One, Billy Prior is suffering from battlefield trauma. The other is shy young fan and fellow poet Wilfred Owen, whose own anti-war writings, encouraged by Sassoon, will go on to make him posthumously famous as well. In the meanwhile, the once-zealous Dr. Rivers begins to question his role of mending patients' minds so that they may simply go back to the front lines.