Psychopathic Villanelle—a young and prolific assassin—leaves a trail of high-profile murders across several countries. MI5 officer Eve Polastri connects a new assassination in Vienna to a series of such killings which she has been researching in her own time.

Following her assignment in Bulgaria, Villanelle’s handler Konstantin is concerned about her increasing recklessness. He informs her that a covert MI6 task force, led by Eve, is investigating her string of assassinations

Villanelle lures Eve to Berlin by using Eve’s name while committing another murder, and trails Eve as she investigates it.

Konstantin punishes Villanelle for her recent unpredictable behaviour by making her work with two other operatives: Nadia and Diego. The three are to assassinate Frank Haleton, Eve’s former MI5 boss, who Eve has discovered is a mole.

There are hints that Elena and Kenny may have a romantic relationship. Villanelle breaks into Eve’s home to talk to her, and takes her phone, which Villanelle uses to track down Frank at the safe house and kill him.

Eve and Carolyn track down Nadia to a Moscow prison, and are allowed to speak to her due to Carolyn’s camaraderie with two Russian Intelligence officers, one of whom is Konstantin.

Eve investigates Anna, Villanelle’s former teacher, with whom she had a deep relationship before Villanelle killed her husband.