Who killed Adam McIntosh in The Better Sister? Details explained

The Better Sister ( Image via YouTube / Prime Video )
The Better Sister ( Image via YouTube / Prime Video )

Alafair Burke's The Better Sister plunges into the dark waters of family ties, trauma, and navigating that delicate balance between truth and self-preservation. The story opens with the gruesome killing of Adam McIntosh, a retired prosecutor, husband, and father. But the crime, terrible as it is, is merely the tip of a significantly more complex iceberg—one consisting of two sisters, a sullen teenager, and the secrets they have all gone to extreme lengths to conceal.

The disintegration of a perfectly coiffed life, in which nothing ever quite is what it seems and everybody has something to conceal, is the focus of the book. Second wife Chloe Taylor, a glossy magazine editor, is the center of everything. She's bringing up Adam's teenage son, Ethan, from his earlier marriage to her sister, Nicky. When Adam is murdered in their Hamptons beach house, Ethan is the first suspect.

With detectives digging deeper and alibi discrepancies surfacing, Chloe and Nicky must confront not just the crime but what caused it. Who actually killed Adam? The solution is a surprise—a surprise that reconsiders loyalty, guilt, and what it actually takes to protect family.


The complex family web in The Better Sister

youtube-cover

The familial dynamics of The Better Sister are anything but typical. Nicky and Chloe are half-sisters who have harbored a reservoir of anger, jealousy, and suspicion between them for many years. Chloe, being the "better" half in the eyes of society, had eventually married Adam after his divorce from Nicky and was thus left to raise Ethan.

Their relationship is already emotionally charged even before the murder reunites them. Teen Ethan is a reserved, watchful teenager and the initial one to be suspected in the investigation. He conveniently happened to be the individual who discovered Adam's body, and suspicion by the police is quick when Ethan's alibi is not perfect.

Chloe grows increasingly defensive and protective of Ethan, and readers can't help but ask what she knows—and what she's doing to protect her son. It's not until readers feel they know the secret, though, that the story actually gains momentum.


The investigation and shifting suspicion in The Better Sister

The longer the investigation continues, the more Ethan is in the spotlight. His alibi is not as good as he'd have liked, and the police begin to toughen up their interrogation. Chloe's attitude offers little assistance—she won't say anything and holds onto what she lets seep to the police. In public, she's a stoic public figure. Behind doors, she's fighting a hurricane of guilt, fear, and maternal instinct.

Nicky, the formerly viewed irresponsible sister, comes back not only to fight for her son, but also to seek the truth. She is not welcomed initially, but as tensions build, she is a necessary piece to solve the mystery. The sisters, though completely shattered, must deal with their past while keeping Ethan from becoming a fall guy for a crime he didn't commit.


Who really killed Adam McIntosh in The Better Sister

youtube-cover

To everyone's astonishment, Ethan did not kill Adam McIntosh in The Better Sister. The killer is Nicky. At the climax of the book, after a dramatic showdown, Ethan tells Nicky about the brutality Adam has been unleashing, specifically on Chloe. Nicky goes to confront Adam at the McIntosh beach house, and there is a ferocious fight. Adam, physically violent and enraged, attacks her. In defense, Nicky kills him.

The deed isn't premeditated; it's an act of sheer self-defense. Yet its implications are significant. Nicky doesn't speak out initially. Instead, she and Chloe consciously behave to rescue themselves and Ethan. It's not merely about evading punishment—it's about restoring agency in a situation where the two women, both, individually, had been silenced or controlled by the very same person.


The cover-up and the framed villain in The Better Sister

When the sisters in The Better Sister finally find out the truth, they take matters into their own hands. Rather than allowing Nicky to go to trial—or allowing Ethan's name to continue getting more and more blackened with suspicion—they concoct a scheme to shift the blame. They create a sketchy, manipulative man, Bill Braddock, a former co-worker of Adam's with his own shabby history.

This dishonesty is immoral but emotionally engaging. The sisters do not come across as heroines or villainesses; they are women faced with impossible choices. They offer false alibis, create false evidence, and conspire to deflect suspicion from themselves and Ethan. Their solidarity, forged in the worst of conditions, is a sign of their resilience, which is also the cost of their decades of silence and denial.


Silence, justice, and protection are themes of The Better Sister

The Better Sister is as much a book about violence as it is a book about the psychological toll of not speaking out. Chloe's silence regarding Adam's abuse, Nicky's shame at losing the past, and Ethan's stoic unhappiness lay the foundation for the unfolding tragedy. The book does not romanticize violence; instead, it excavates the structural and affective topographies within which abuse can occur.

Nicky's self-defense becomes a lens through which to consider responsibility in the novel. She may have killed Adam, but the novel encourages us to think about how everything that had happened up until then came to pass—i.e., those people who could have spoken up sooner but did not. The overall theme is less "who killed Adam?" as it is "how did this occur?"


Justice, but at what cost

Finally, the official explanation falls far short of the truth. Bill Braddock is framed, the public is made secure, and the case is closed. Chloe and Nicky are acquitted, and Ethan's reputation is restored. But the psychological impact remains. The sisters have rescued Ethan and themselves, but at a price—inner and interpersonal. The novel concludes not with closure, but with an unsettling feeling of uncertainty.

While The Better Sister delivers the necessary surprises of a murder mystery, the book is ultimately a story about the choices women make under extreme pressure, when justice is not available through the legal system, and protection is self-initiated. It's an account of just how far people will go to guard the ones they love, and how truth, once concealed, can transform everything it touches.


So, who killed Adam McIntosh in The Better Sister? Simple: Nicky, self-defense after years of physical abuse, silencing, and psychological manipulation. But the larger picture won't let the reader have just that solution.

Alafair Burke masterfully pens a world where justice is an elusive thing, motives are muddied, and family love demands impossible decisions. The story is solvable—but what matters is the harrowing path it takes to get there.

Also read: The Better Sister is a somewhat decent portrayal of how a tumultuous sibling connection can bring their worlds down: Here's why

Edited by Sezal Srivastava