In the last idyllic summer of 1914, the battle lines are already drawn. In Cambridge, the golden June days seem timeless. But for Joseph Reavley the summer is shattered by his parents’ deaths in a car accident. Bringing the terrible news, his brother reveals that their father, a retired MP, had been travelling to see him about a sinister plot he had discovered. Matthew’s job in the secret service means that he would understand the mysterious document their father possessed, but now it is nowhere to be found. Returning after the funeral with their two sisters, Joseph and Matthew become convinced that their parents’ house has been searched. As their suspicions grow, they visit the scene of the crash and find subtle evidence that their deaths may not have been accidental after all.