Anna Witherall's carefully constructed life of domestic bliss is shattered when her past in secret intelligence resurfaces, forcing her to choose between protecting her family and disappearing from their lives forever. Anna, who works for an aspirational magazine, appears to have it all: a loving husband, David, and three-year-old twin daughters, Stella and Rose. However, a dark secret from her time in intelligence threatens to expose her and endanger her family. As she is drawn back into the clandestine world she tried to leave behind, Anna realizes that someone she trusted is determined to make them all pay, and her only option for their safety is to abandon them permanently.

The Most Difficult Thing has been met with considerable acclaim, with reviewers frequently highlighting its compulsive nature and stylish execution. Critics have praised its seamless blend of contemporary espionage with domestic suspense, noting its ability to create a highly charged examination of betrayal. The book is described as addictive and enigmatic, drawing readers into its intricate plot from the very first page. Its ability to keep readers on edge is a recurring theme in its reception, solidifying its status as a compelling page-turner.