Killers of a Certain Age belongs to the contemporary thriller genre though it departs from it in some ways to advance Raybourn’s interests in gender, power, and women’s inner lives. Thrillers rely on narrative tension, suspense, and frequently, a quest for survival. Raybourn follows this convention in most respects, as Billie and her friends soon realize their lives are in danger and their retirement cruise will be far from peaceful. Few action thrillers feature an ensemble of women. This cast of characters, together with Raybourn’s explicit attention to gender politics, establishes the genre as more feminist than others of its kind.

While most thrillers rely on a cascade of threats and a short timeline for a protagonist to manage them, Raybourn has an abiding interest in helping the reader understand how the four women became who they are today. The first chapter concerns the team’s first mission, immersing the reader in their past before introducing the challenges of the present. This allows Raybourn to underline that the women’s struggle for survival and success has always involved a secondary battle with sexism: Vance underestimates them in the past while the assassination attempts against them in the present involve both sexism and ageism.