My Sister Is Going to Kill Me by Nina Simon: The Liar and the Polygraph

My Sister Is Going to Kill Me by Nina Simon

Fourteen days on the river, no phones, no exit, and a founder who never boards the helicopter.

Liv Chisholm detects deception for the State Department. Her sister Mandy lies for sport. On their tenth annual sister trip, a comped rafting expedition down the Grand Canyon, the CEO sponsoring the trip fails to arrive and then turns up dead. Simon's follow-up to Mother-Daughter Murder Night is funny, fast and genuinely well plotted, though its suspect pool is larger than it can properly feed.
  • Publisher: William Morrow
  • Genre: Mystery, Thriller, Crime, Contemporary
  • First Publication: 2026
  • Language: English

Everyone on the Essence Quest is handed a white ball cap with a silver logo on the crown, and for the first days on the river those caps stay exactly as blank as they look. Then Colorado silt works into the cotton, mud settles into the places where the weave sits raised, and the white thread stitched into white fabric finally has something to hold on to. Each hat turns out to have been carrying a private sentence the entire time, addressed to whoever happened to be wearing it. That trick is a fair advertisement for My Sister Is Going to Kill Me by Nina Simon: a mystery that hides its worst news in plain sight and then waits for the weather to develop it.

The setup is a freebie with strings. Babette Botanique, a skincare company on the verge of launching a mood-altering product called CareFree, has organised an influencer expedition down the lower Grand Canyon and comped two spots. Liv and Mandy Chisholm take them for their tenth annual sister trip. Fourteen days on the water. No phones. No road out. The founder is supposed to drop in by helicopter on the second morning, and she does not.

Two Sisters and One Polygraph

Liv Chisholm works for the State Department, where her specific talent is reading people for deception, and she has built an entire personality on the principle of never lying herself. Mandy teaches high school art and lies the way other people clear their throats: constantly, harmlessly, mostly to make the room a pleasanter place to stand in. They love each other with the specific exhaustion of siblings who have been running the same argument since childhood.

My Sister Is Going to Kill Me by Nina Simon alternates their chapters, and the alternation is not decoration. It is the plot. Liv interrogates; Mandy charms. Liv can tell that someone is lying and cannot get them to talk. Mandy can get anyone to talk and has no idea what to do with what they say. The book’s cleverest structural decision is to separate them physically for a long central stretch, so that each sister has to attempt the other one’s method with no coaching, badly, and then live with the results.

By the closing chapters of My Sister Is Going to Kill Me by Nina Simon, the accumulated case has been assembled from both halves, and neither half would have been sufficient. That is a great deal more craft than the breezy cover suggests.

What Works

  • The canyon is a location, not a backdrop. Eddies, scout lines, the physics of a raft pinned sideways against a boulder, why rafting without a personal flotation device is both illegal and idiotic. Simon has clearly been down this river, and the acknowledgments confirm it, along with a candid note about the three geographic liberties she took.
  • The wellness satire has actual teeth. CareFree is derived from a plant, and the plant has a waste product, and the waste product has to be disposed of by somebody. The novel is funny about eye cream and completely unsentimental about supply chains.
  • The comedy is load-bearing. A river guide in a self-processed sheepskin loincloth. A teenager building an emergency flotation belt out of branded water bottles and paracord. Paddles improvised from camping chairs and a cast-iron skillet. The jokes keep working because the danger underneath them never softens.
  • The clue placement is honest. Almost everything the ending needs has been on the page for two hundred pages, usually disguised as scenery or small talk.

Where It Strains

  • The suspect pool is bigger than My Sister Is Going to Kill Me by Nina Simon can properly feed. Three siblings from the founding family, a fired dermatologist, a marketing lead, an influencer, a chaperone, four guides and a gatecrashing relative. Several of them get one distinguishing trait and are then parked until required.
  • The solution runs on improvisation. A great deal of the plan collapses early and is rebuilt on the fly, and the novel is upfront about this, which is honest but does soften the pleasure of a scheme clicking shut.
  • Motive arrives by paperwork. The why of the case is genuinely good and genuinely nasty, and it is delivered almost entirely across two conversations conducted over a contract folder in the heat.
  • The con-man father is a type. Charming, unreliable, allergic to the police, always one deal away. He is enjoyable, and he never surprises you.

Why My Sister Is Going to Kill Me by Nina Simon Will Not Stay Locked

Locked-room mysteries usually depend on the room staying locked. Simon’s canyon does the opposite. It keeps opening. Boats are stolen, groups split, a party goes downstream while another stays behind with a body, and the geography that isolates everybody also keeps rearranging who is isolated with whom. The Park Service is candid that a Grand Canyon whitewater trip is a serious wilderness commitment rather than a theme-park ride, and the novel takes that seriously enough to make the logistics of a murder investigation genuinely difficult. There is no coroner. There is no evidence bag. And there is a tarp, a shovel improvised from a broken chair, and a decision about whether to commit a federal crime before lunch.

That constraint produces the best sustained sequence in My Sister Is Going to Kill Me by Nina Simon, in which the investigation and the survival problem become the same problem, and every question Liv wants to ask costs her river miles she cannot get back.

Who My Sister Is Going to Kill Me by Nina Simon Is For

Reach for it if you liked the amateur-sleuth warmth of Simon’s debut and want the same voice with a harder edge. Reach for it if you want a mystery where the sleuthing pair actually have a relationship rather than a dynamic. And reach for it if you want to be outdoors.

Skip it if you need a tightly cast puzzle where every suspect is fully realised, or if you want a coldly rational detective, because My Sister Is Going to Kill Me by Nina Simon is deliberately about the limits of that posture.

Read These Next

If the sisters are what kept you turning pages in My Sister Is Going to Kill Me by Nina Simon, these are the natural follow-ons.

  1. Mother-Daughter Murder Night by Nina Simon. Her debut, and the obvious starting point. Three generations of women, a Californian slough, and the same insistence that family friction is the best interrogation tool available.
  2. Drop Dead Sisters by Amelia Diane Coombs. Sisters, a body and a great deal of unresolved sibling accounting.
  3. The Guest List by Lucy Foley. For the pure closed-circle pleasure of a remote location and a cast who all have something to hide.
  4. Where the Crawdads Sing by Delia Owens, if what you want next is the landscape rather than the puzzle.
  5. The Thursday Murder Club by Richard Osman, for readers who came for the comic ensemble and would happily lose the whitewater.

The Last Word on My Sister Is Going to Kill Me by Nina Simon

My Sister Is Going to Kill Me by Nina Simon delivers a generous, propulsive, slightly overpopulated mystery with an excellent central pair and a motive that is much colder than the packaging implies. The plotting is fair, the setting is earned, and the ending lands a final line that reframes eight hundred miles of argument in five words.

Simon has written a book about two women who have spent thirty years accusing each other of being the difficult one. Its real argument is that a family gets to keep both the liar and the lie detector, because sooner or later you will need whichever one you have been refusing to become.

More on this topic

Comments

LEAVE A REPLY

Please enter your comment!
Please enter your name here

  • Publisher: William Morrow
  • Genre: Mystery, Thriller, Crime, Contemporary
  • First Publication: 2026
  • Language: English

Readers also enjoyed

Before You Were Anne by Emiko Jean

A spoiler-free review of Before You Were Anne by Emiko Jean: a woman dead at the foot of her stairs, her daughter gone, and a detective who has never known her own first name.

A Snake Among Swans by Hannah Kaner

A spoiler-free review of A Snake Among Swans by Hannah Kaner: a hostage bride, a conquering swan king, a forest that sells power for memory, and a running bill that comes due.

We Already Dug the Grave by Emma C. Wells

A spoiler-free review of We Already Dug the Grave by Emma C. Wells: two sisters, one shovel, a decade of silence, and a set of tea leaves that have said the same word for ten years.

Big Bad Wolf by Laurie Gilmore

A spoiler-free review of Big Bad Wolf by Laurie Gilmore: the first Maple Hollow book is a rewrite of a novel she published three years ago under another name, and knowing that changes how you read it.

The Witches of Cambridge by Alice Hoffman

A spoiler-free review of The Witches of Cambridge by Alice Hoffman: two Radcliffe freshmen, a secret society older than Harvard, and a hanging tree that has been standing on the Common the whole time.

Popular stories

Liv Chisholm detects deception for the State Department. Her sister Mandy lies for sport. On their tenth annual sister trip, a comped rafting expedition down the Grand Canyon, the CEO sponsoring the trip fails to arrive and then turns up dead. Simon's follow-up to Mother-Daughter Murder Night is funny, fast and genuinely well plotted, though its suspect pool is larger than it can properly feed.My Sister Is Going to Kill Me by Nina Simon