One day in 1917, Elinor has a sudden premonition that Toby will not return from France. Three weeks later the family receives a telegram informing them that Toby is “Missing, Believed Killed” in Ypres. However, there is no body, and Elinor refuses to accept the official explanation. Then she finds a letter hidden in the lining of Toby's uniform; Toby knew he wasn't coming back, and he implies that fellow soldier Kit Neville will know why.

In 1917, Siegfried Sassoon, a combat officer and poet, writes a letter publicly disavowing the war. He is found to be "mentally unsound" and is sent to Craiglockhart War Hospital, where there is a psychiatrist renowned for curing such sad cases.

Paranoia threatens to destroy the very fabric of British society as the public seeks scapegoats in the spring of 1918.