Motherless and irrepressibly curious, Esme spends her childhood at her father's feet as he and his team gather words for the very first Oxford English Dictionary. One day, she sees a slip of paper containing a forgotten word flutter to the floor unclaimed. And so Esme begins to collect words for another dictionary in secret: The Dictionary of Lost Words. But to do so she must journey into a world on the cusp of change as the Great War looms and women fight for the vote. Can the power of lost words from the past finally help her make sense of her future?