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, Villanelle.

In the aftermath of her recent assignment, Villanelle is ordered to take a break. Never one to do as she's told, she goes ahead with her next mission regardless. Meanwhile, Eve is given a dream opportunity to join a secret MI6 unit tracking Villanelle and the shady organization she works for.

Villanelle's mission is proving anything but straightforward, forcing her to take drastic measures. Meanwhile, Eve makes a shocking discovery, which leads her right to Villanelle and an electrifying confrontation from which neither will emerge unscathed.

Eve is reeling from her act of violence against Villanelle and doesn't know whether she is alive or dead. A paranoid and severely injured Villanelle manages to get herself to the hospital for treatment. Carolyn approaches Eve with an intriguing opportunity.