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.

When Villanelle kills a Chinese colonel at a kink clinic in Berlin, Eve and Bill travel out to investigate. While Eve and Bill chase up a number of promising leads, Villanelle enjoys the cat-and-mouse of their proximity. But as they draw closer, Eve comes to realize that this is much more than a game.

Having survived a terrifying close call with Villanelle, Eve now has the mole ensconced in a safe house and is buzzing. They have an exciting opportunity to glean information and crack this thing open.

A female assassin is taken into custody in Russia, and Eve and Carolyn head out to Moscow to negotiate access. She could hold the key to the organization that runs Villanelle. Meanwhile, Villanelle is smuggled into the same Russian jail. It's a grim and brutal place, where not even Villanelle is safe.

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.

Carolyn introduces Eve to her new team before Eve briefs them on the Villanelle case. Villanelle, needing to lie low while she recovers, finds a good Samaritan to take her in and care for her.

Villanelle decides to take matters into her own hands on a trip to Amsterdam. Carolyn is called in to face the music with her boss. After the discovery of another dead body, Eve and her new team make a break in their case.

The MI6 team make a pact with the devil in order to get information from The Ghost. A visitor from Broadmoor comes with a dire warning, while Eve and Villanelle find themselves closer than ever.

The point of no return: Villanelle uses her unrivaled infiltration skills to immerse herself in the world of a new target. Their relationship on the rocks, Eve and Niko confront each other about their future.

Villanelle dives deep into the dangerous world of her target under the guise of her newfound persona, Billie. Eve may have worrying competition for Villanelle's affections.

Eve's mission is disastrously compromised. Carolyn briefs Eve on her current status as an employee of the British government and leaves Eve's future in her own hands. Villanelle does everything she can in order to get to her ultimate target.