Laurel is four and a half, and she does not want to sit on Santa’s lap. She wants to study the elves. While her big sister Cassie waits in a mall line in Denver, Laurel notices a fresh burn on one elf’s neck and quietly tells her she is free to leave, that nobody will hurt her, not even Santa. Then she catches Santa’s eyes drifting as he lies to another child. It is played for laughs, and it is funny, but it also tells you what kind of book Dangerous Impulses by Jennifer Lynn Barnes is: a Christmas story in which every cheerful surface gets read for what is underneath.
Dangerous Impulses by Jennifer Lynn Barnes Plot Summary
It is 19 December, and the Naturals, teenagers trained by the FBI to read liars, killers and emotions, now live in a house in Denver near Cassie’s grandmother. Nonna calls a briefing of her own: she wants Agent Veronica Sterling and FBI Director Tanner Briggs, once married, engaged again by Christmas Eve, and she wants the kids to find out why Sterling keeps saying no. The same afternoon, Sterling brings them a four-year-old file flagged by Sloane’s search program: a runaway who died of natural causes and was found in the snow, washed, combed and arranged in a snow angel. Nobody killed her. Somebody needed her. And every December since, something similar has happened.
Project Mistletoe Is the Real Case
The first thread in Dangerous Impulses by Jennifer Lynn Barnes, and the stronger one, is the matchmaking. Barnes builds it like an investigation. Cassie profiles Sterling during a midnight rescue from a karaoke bar, where Michael is singing Christmas songs in reindeer antlers and Sterling, astonishingly, takes a shot of tequila. Michael reads her face, Lia listens for half-truths, Sloane runs the numbers, and Dean supplies the history he shares with both agents. Later the gang breaks into Sterling’s apartment and reads it like a crime scene: three blankets heaped on one sofa, an unused mixer in a hopeful shade of blue, a twin bed bought for a child who has never slept there.
This is where the novel is at its best. The romance plot turns out to be about family, about who leaves, who stays and who is afraid of being the one to go. Sterling and Briggs are written as adults with a long, bruised history, and Barnes lets them be funny with each other as well as sad. The banter between the five teenagers is quick and often very funny; Michael and Lia, mid-breakup, are as combustible as ever, and Sloane’s attempt to model love with hundreds of sticky notes is a small comic masterpiece.
The Snow Angel Case Runs Underneath
The counter-thread is the cold case, and it supplies the title. Cassie and Dean profile the stranger in second person, and short interludes put you inside his head as he climbs overpass railings and stares into the snow. The clues are odd and specific: an octagon shoveled around each scene, a blanket, a stick placed in a sleeping man’s hand. When the pattern in Dangerous Impulses by Jennifer Lynn Barnes finally clicks, the explanation is both elegant and genuinely sad, which is rarer than it should be in YA crime.
The case is also, honestly, the smaller story. For long stretches it waits on database searches while the Christmas plot takes the stage, and a reader who wants the menace of the earlier Naturals books may find the stakes low. Cassie’s training in criminal profiling is on full display, but the danger rarely reaches the team itself.
Where It Gives Ground
- The case resolves partly offstage. The final confrontation happens away from Cassie, reported in a few pages, after most of the hard work has been done by Sloane’s software.
- The tics repeat. Certain refrains about Cassie and Dean, Nonna’s sayings and Michael’s lines return so often that they start to feel like stage directions.
- The break-ins are played as larks. Searching an agent’s home and pocketing a drive of classified files is treated as harmless fun, and the book only half-reckons with it.
- It is not a starting point. Dangerous Impulses by Jennifer Lynn Barnes assumes you remember the cast, the Masters and how Bad Blood ended.
Where Jennifer Lynn Barnes Places Book Five
Publication order, which is also the order to read them in:
- The Naturals (2013)
- Killer Instinct (2014)
- All In (2015)
- Bad Blood (2016)
- Twelve (e-novella, 2017)
- Dangerous Impulses (2026)
The fifth novel picks up only months after Bad Blood, even though a decade passed in the real world. None of the earlier Naturals books has a review on this site yet.
Do You Need the Earlier Books?
Yes. Dangerous Impulses by Jennifer Lynn Barnes explains enough to follow the plot, but its emotional weight comes from what happened in the first four books, and the opening chapters casually spoil several of their biggest turns. If you have read them, even years ago, you will be fine within a chapter. If you have not, start with The Naturals.
Read These Next
- A Good Girl’s Guide to Murder by Holly Jackson: a teenage investigator, a cold case and the cost of getting it right.
- My Killer Family Reunion by Dinesh Thiru: murder and messy family loyalty in one holiday-ready package.
- Glorious Rivals by Jennifer Lynn Barnes: the author’s puzzle-box side, with higher stakes.
- What We Did to Survive by Megan Lally: a tense YA thriller for readers who want the danger turned up.
About Jennifer Lynn Barnes
Barnes is best known now for the Inheritance Games, and she brings that series’ gift for team banter back to the series that first made her name. She has written more than twenty-five young adult novels, including The Final Gambit and The Gilded Blade.
- She studied cognitive science at Yale and earned her PhD there in 2012, which shows in how carefully the profiling is described.
- The Final Gambit won the 2022 Goodreads Choice Award for young adult fiction.
- The Naturals first appeared from Disney-Hyperion; Little, Brown has since repackaged the series, and the acknowledgments promise more books to come.
The Last Word
Dangerous Impulses by Jennifer Lynn Barnes is less a thriller than a homecoming, a Christmas visit with characters many readers have missed for ten years. The mystery is slight and the jokes sometimes repeat, but the warmth is earned, and the quiet case at its center ends on grace rather than gore. It came out on 3 November 2026, and it is the rare series return that leaves you wanting the family more than the next body.
Content notes tap to reveal
A teenager’s body posed after a natural deathTwo sheep killed, one bloodily, described through crime scene photosSuicidal thoughts in the stranger’s interludesA fatal car crash involving children, in the pastPTSD, nightmares and flashbacks to violence from earlier booksA small child recovering from abuse in a cultDrinking by eighteen- and nineteen-year-olds, moderate swearingHeat level: kissing only, including a sapphic kiss; nothing more on the page
Where to read Dangerous Impulses
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