My Sister, the Serial Killer, is a novel by Nigerian-born British writer Oyinkan Braithwaite, originally published in the UK in 2019. Set in Nigeria’s largest city, Lagos, this darkly satirical, structurally experimental crime story about the extremes of family bonds bears an unusually revealing and literal title, and it has been longlisted for the prestigious Booker Prize. The novel was also shortlisted for the Women’s Prize for Fiction and the 2019 Amazon Publishing Readers’ Awards, and it won the LA Times Award for Best Crime Thriller in 2019 and Anthony Award for Best First Novel (one of the most respected awards for crime fiction in the US).

Oyinkan Braithwaite graduated from Kingston University, London, with degrees in creative writing and law and has won prizes for her spoken word slam poetry. The novel has been translated into several languages and the film adaptation is in preparation.

This study guide uses the 2018 e-book edition published by Doubleday.

Plot Summary

Korede, a young nurse of average, typically Nigerian looks, works in a hospital in Lagos. She leads a highly organized and sterile existence, dedicated to the protection of her younger, arrestingly beautiful sister, Ayoola. Ayoola serially kills men who worship her, and Korede feels compelled to cover her sister’s tracks and find ways to stop her from killing again.

The novel begins with Ayoola’s third victim, the perceptive and poetic Femi, whose body the sisters dispose of in one of Lagos’s many lagoons. Ayoola carries a knife that she took from their dead, abusive criminal of a father, and her kills tend to be bloody and messy. Korede is obsessed with cleaning the traces, and this obsession slowly seeps into the rest of her life. She is in love with handsome Dr. Tade Otumu, but a chance meeting between Ayoola and Tade leads to his infatuation with Ayoola. Since Korede does not have friends, she confides her troubles in Muhtar Yautai, a patient in a coma, the victim of a traffic accident.

Korede worries that Ayoola might be a sociopath, as she does not show any signs of remorse and even tends to see herself as the victim. This mindset reminds Korede of their father, whose behavior within the family was cold, brutal, uncaring, and extremely self-centered, although in front of others he knew how to be charming—just like Ayoola. Still, influenced by the passive mother who brought her up, Korede protects her sister at all costs.

When Ayoola’s casual, married lover and sponsor, Gboyega, dies during their trip to Dubai from an apparent drug overdose, Korede fears her sister is spiraling into uncontrollable madness. Muhtar wakes from his coma, revealing that he has heard and understood Korede’s confidences. He supports her in making sure she saves Tade’s life while reassuring her that he will keep her confessions secret.

Tade prepares to propose to Ayoola, disbelieving Korede’s repeated warnings, so Korede destroys the diamond ring he has bought and stages a theft. Soon, she receives a call from Tade’s house; Ayoola tried to stab him, they fought, and when she rushes there, Korede finds Ayoola with the knife stuck in her belly. She drives her sister to the hospital, where Ayoola undergoes an urgent surgery and survives. In a final attempt to protect her sister, Korede threatens Tade that she will accuse him of brutally attacking Ayoola for refusing him if he tells the police what has transpired. When Ayoola wakes up, however, Ayoola tells the police the same story, and the police arrest Tade for assault. The medical board revokes his medical license, and he goes to prison.

Muhtar leaves the hospital and asks Korede to stay in touch. She considers him a friend but feels her sister needs her undivided loyalty, so she destroys the note with his phone number. She then goes to meet Ayoola’s new admirer: potential victim number five.