A popular nonfiction writer in the UK specializing in historical true crime, Robins delves into fiction in White Bodies, an intimate story of twin sisters Tilda and Callie, separated by Tilda’s blooming relationship with a man. Tilda is a starlet on the cusp of a bright career. Callie has long existed in her sister’s shadow, making peace with this lesser role, content to work at a small local bookstore. Callie tries to make peace as well with Tilda’s new financier beau, Felix, but finds that a more difficult fit.

Included in some of the couple’s initial outings, Callie is pleased, even grateful, though the charismatic Felix is a mystery to her, charming and frighteningly attractive yet moody and controlling. Watching Tilda fall under his spell, Callie is at first suspicious then certain there is something amiss in the relationship. Felix takes charge of everything: vacation plans, Tilda’s career, redecoration of Tilda’s flat. Callie’s doubt becomes certainty as Tilda withdraws, asking for privacy: “She’s wearing a long-sleeved T-shirt and she has a tin gray cotton scarf around her neck…but I can see her bony knuckles and bitten nails… and I’m caught up in anxiety about her.” Callie has facilitated the current contretemps with Felix, her thinly-veiled accusatory remarks offending Felix and Tilda, her welcome withdrawn as the couple expresses a desire to be alone in this early stage of their romance.

To be sure, it is a predictable complication, difficult but not insurmountable if not for Callie’s lifelong obsession with Tilda’s life. In chapters revealing the girls’ childhood, Callie casts herself as lesser, dark-haired to Tilda’s golden tresses, curvy instead of svelte, socially awkward, never popular. In her solitary existence post-Felix, Callie discovers a website about the characteristics of dangerous men, controllingmen.com. Given the need for anonymity, Callie makes friends; Scarlet and Belle understand her concerns and share their own. Her days suddenly fuller, Callie freely shares her fears as well as listening to her new friends’ worries for “women in danger.” The movie “Strangers on a Train,” Hitchcock’s psychological thriller about the disposal of an unwanted spouse, is a topic of conversation, but Callie prefers to talk about Tilda, scarcely interested in the others women’s stories.

The stage is set for drama, even murder: Tilda’s overbearing lover holding her hostage, Callie increasingly fearful for her sister, immersed in a website where she is buoyed by two new friends with similar concerns; and the lifelong imbalance of twins with separate identities but a unique bond, one an extrovert, the other painfully shy, the seeds of conflict sowed with jealousy and fear. While other characters act out their roles, there are really two protagonists who drive White Bodies. Seen through Callie’s eyes, events carry an aura of danger, Tilda’s viewpoint made suspect by an unwillingness to confide her true feelings. The vaguely sinister becomes urgent, someone’s life at stake. Robins navigates these protagonists, especially Callie, with an uncanny skill, Tilda seemingly unable or unwilling to extricate herself from Felix, human nature at its most deliciously unpredictable.