MI5 security officer Eve Polastri is bored in her job and yearns for a more exciting life. When a Russian politician is murdered, Eve is tasked with protecting the only witness and soon finds herself on a collision course with a violent and extraordinary assassin.
Eve's life as a spy is not adding up to what she had hoped it would be when she started. She is a bored, very smart, MI5 security officer who is very desk-bound. Villanelle is a very talented killer, mercurial in mood, who clings to the luxuries of her job. Eve and Villanelle go head to head in a fierce game of cat and mouse, each woman equally obsessed with the other as Eve is tasked with hunting down the psychopathic assassin.