Killer Instinct

Name: Killer Instinct (The Naturals, #2)
Author: Jennifer Lynn Barnes

by Jennifer Lynn Barnes

Genre

Young Adult, Mystery, Thriller, Crime

Year

2014

Pages

376

Contents

Overview

Killer Instinct follows Cassie Hobbes and the other teenage Naturals, a group whose unusual gifts for profiling, reading emotions, detecting lies, and analyzing patterns make them valuable to the FBI. After a rare success rescuing a kidnapped child, the team is still carrying old trauma when a new supervisor, Agent Veronica Sterling, arrives to impose discipline and evaluate whether the program should survive.

The central conflict begins with a murder at Colonial University that appears to imitate the crimes of Daniel Redding, the imprisoned serial killer who is also Dean Redding’s father. As Cassie, Dean, Michael, Lia, and Sloane struggle with rules, loyalties, and emotional fallout, the case forces them to confront the dangers of using damaged teenagers to hunt killers. The book blends psychological suspense with themes of control, trust, family legacy, trauma, and the cost of turning instinct into investigative work.

Plot Summary ⚠️ Spoilers

Cassie Hobbes and the Naturals begin the story with a victory: their combined skills help Agent Briggs rescue six-year-old Mackenzie McBride from the McBrides’ deceptive attorney. The success briefly restores morale and reinforces the team’s bond. Cassie, Dean Redding, Michael Townsend, Lia Zhang, and Sloane Tavish celebrate, but the relief is complicated by romantic tension between Cassie, Dean, and Michael, and by lingering trauma from Agent Locke’s betrayal and Cassie’s unresolved grief over her mother.

The mood changes when Special Agent Veronica Sterling moves into the Naturals’ house as their new supervisor. Sterling is controlled, severe, and skeptical of the program. Cassie quickly profiles her as a profiler with personal history tied to Briggs and Dean, and the team learns Sterling is Director Sterling’s daughter, Briggs’s former partner, and Briggs’s ex-wife. She imposes GED work and tighter rules, especially because Dean was originally allowed into the program under an agreement that he would work only cold cases.

A new case makes those limits impossible to ignore. Emerson Cole, a Colonial University student, is found murdered in a ritualistic display resembling the methods of Daniel Redding, Dean’s imprisoned serial-killer father. The similarities devastate Dean, who reveals that his father forced him to watch murders as a child. Sterling and Briggs take the case, but Cassie, Lia, and Michael secretly infiltrate a Colonial University party to gather information. They learn that Emerson was in Professor George Fogle’s serial-murder class, that Fogle was writing about Daniel Redding, and that Emerson may have been involved with him. Students including Geoffrey, Bryce Anderson, Derek, and Gary Clarkson, known as Clark, become possible leads.

The investigation keeps shifting. Dean visits Daniel Redding in prison to extract information, while Cassie and Sterling are forced to observe. Redding manipulates Dean, hints that Fogle has a cabin near Catoctin, and suggests that the important letters he received came from a student rather than the professor. Cassie notices that Sterling bears an R-shaped brand; Sterling later reveals Daniel Redding once held her captive and that Dean branded her at her request to convince Redding that Dean had turned against him. The revelation explains Sterling’s protectiveness toward Dean and her rigid insistence on protocol.

The Colonial student lead seems promising until a video proves all 307 students in Fogle’s exam, including Geoffrey and Clark, were in the lecture hall when Emerson died. Meanwhile the FBI finds Fogle dead, and the team learns more about old wounds: Sterling left the FBI after the Nightshade case, in which Scarlett Hawkins, Judd Hawkins’s daughter and Sterling’s friend, died. Dean also traces one of Daniel Redding’s prison visitors to his hometown, Broken Springs. Cassie, Dean, and Michael secretly visit Trina Simms, a devoted admirer of Daniel Redding, and meet her hostile son Christopher Simms. Trina’s worshipful attitude rules her out as the killer, but Christopher’s black truck and aggression make him suspicious.

After the unauthorized trip, Sterling tightens restrictions and fits Cassie with an ankle tracker. Then Trina Simms is murdered while Christopher is with Briggs, giving him an alibi. Dean realizes the case is not a simple copycat. A king of spades found in Trina’s pocket confirms Daniel Redding’s direct influence, and Sterling and Cassie reframe the offender as an apprentice rather than a partner. Redding appears to be orchestrating events from prison, using younger killers to act out his control and to reach Dean.

Redding demands that Cassie be brought to him. In a controlled prison interview, Cassie asks paired questions designed to let Lia identify lies, but Redding gives contradictory answers that all read as true. Sloane realizes the explanation: there is more than one apprentice. Soon Gary Clarkson is found murdered at Colonial, while DNA from Trina’s fingernails proves Clark killed Trina. The team deduces a mutual-murder system: the apprentices selected victims for each other, creating alibis in a Strangers on a Train pattern. Clark likely chose Emerson, but another apprentice killed her; Christopher chose Trina, but Clark killed her; then the more organized apprentice killed Clark.

The FBI arrests Christopher Simms with a kill kit, apparently preventing another murder, but Cassie cannot let the pattern rest. She realizes someone else must have selected Christopher’s intended coffee-shop victim and may have killed Emerson. When Director Sterling calls to report that Christopher has died in his cell, Sterling and Cassie suspect foul play. Outside the house, they are ambushed by Anthony Webber, the antagonistic prison guard from Dean’s earlier visit. Webber’s position explains how Daniel Redding learned about Cassie and how Christopher could be killed in custody. He abducts Sterling and Cassie.

Cassie and Sterling wake bound in an isolated cabin. Cassie believes her ankle tracker will bring help, but Sterling admits she never activated it, using it only as a deterrent. Webber returns and releases Cassie into the woods to hunt her. Cassie evades him, wounds him with a rock, and survives until Agent Briggs arrives and shoots Webber. Briggs explains that although Sterling had not activated the tracker, her paperwork allowed the FBI to activate it remotely. Dean arrives with Briggs, and after the terror of nearly losing each other, Cassie and Dean finally choose each other openly.

Afterward, Briggs takes Cassie to Webber’s apartment so she can understand what happened. Webber’s journals reveal that Daniel Redding exploited him after Webber transferred to Redding’s prison block, used him to track Briggs and Dean, and developed apprentice tests after learning about Agent Locke’s murders. Webber killed Emerson, Fogle, Clark, and Christopher, facilitated the larger game, and tried to surpass the others. Cassie returns home steadier, but Michael realizes she has chosen Dean and lashes out in hurt, fracturing their relationship.

Three weeks later, after the team takes the GED, Sterling returns to the house. She has reported the off-book program to the director of National Intelligence, forcing formal oversight. Major Judd Hawkins becomes the Naturals’ advocate with final authority over deviations from protocol, while Sterling and Briggs will supervise. The teens must stay behind the scenes until they are eighteen, but they are officially cleared to consult on active cases. The ending leaves the team changed by trauma and loss, but with clearer protections, sanctioned purpose, and a more honest structure around their dangerous work.

Characters

Cassie Hobbes

Cassie is the narrator and a Natural profiler whose empathy lets her enter killers’ mindsets but also makes her vulnerable to manipulation and guilt. Her investigation of the Redding-linked murders, her conflict with Agent Sterling, and her choice between Dean and Michael drive both the case and the emotional arc.
Dean Redding

Dean is a Natural profiler and Daniel Redding’s son, making the Colonial University case intensely personal when the murders mirror his father’s methods. His struggle to reject his father’s legacy while accepting support from Cassie and the team is central to the story.
Michael Townsend

Michael is the team’s emotion reader, using humor and provocation to manage anger, fear, and vulnerability. He supports Cassie and Dean during the case, but his feelings for Cassie and rivalry with Dean fracture the group after Cassie chooses Dean.
Lia Zhang

Lia is the team’s human lie detector, sharp, manipulative, and fiercely protective of Dean. Her ability to read Daniel Redding’s truthfulness helps expose the multi-apprentice scheme, while her loyalty complicates the team’s risks and secrets.
Sloane Tavish

Sloane is the Naturals’ statistician and pattern analyst, translating videos, schedules, geography, and probabilities into leads. Her insights help collapse false suspect pools, identify the possibility of multiple apprentices, and ultimately point the team toward Cassie’s tracker.
Agent Briggs

Agent Briggs leads the Naturals program and serves as the team’s main FBI handler. His history with Sterling, Dean, and Daniel Redding puts him at the center of the case, and he ultimately rescues Cassie by activating her ankle tracker and killing Webber.
Agent Veronica Sterling

Agent Sterling is the Naturals’ new supervisor, Director Sterling’s daughter, and Briggs’s ex-wife. A survivor of Daniel Redding’s captivity, she begins as a strict evaluator but becomes an advocate for restructuring the program with real oversight and protection.
Judd Hawkins

Judd is the guardian of the Naturals’ house and a steady authority figure who distrusts reckless Bureau choices. His daughter Scarlett died in the Nightshade case, and by the end he becomes the program’s official advocate with final say over protocol deviations.
Daniel Redding

Daniel Redding is Dean’s imprisoned serial-killer father and the mastermind behind the apprentice murders. From prison, he manipulates admirers, taunts Dean and the FBI, and designs the case as a psychological game about control, legacy, and replacement.
Anthony Webber

Webber is a prison guard who becomes Daniel Redding’s most organized apprentice. He facilitates Redding’s communications, kills Emerson Cole, Professor Fogle, Gary Clarkson, and Christopher Simms, abducts Cassie and Sterling, and is killed by Briggs during Cassie’s rescue.
Christopher Simms

Christopher is Trina Simms’s protective and hostile son, initially suspected because of his aggression and black truck. He is later revealed as one of Redding’s apprentices, arrested with a kill kit, and murdered in custody by Webber.
Trina Simms

Trina is a devoted admirer of Daniel Redding who believes in his innocence and imagines a future connected to Dean. Her murder by Gary Clarkson exposes the apprentice pattern and deepens Daniel Redding’s manipulation of Dean.
Gary Clarkson

Gary Clarkson, called Clark, is a student in Professor Fogle’s class who was fixated on Emerson Cole. His DNA proves he killed Trina Simms, and his own murder reveals that Redding’s scheme involves multiple apprentices selecting victims for each other.
Emerson Cole

Emerson is the Colonial University student whose ritualized murder launches the main investigation. Her ties to Professor Fogle’s class and her alleged relationship with Fogle shape the early suspect pool and the later apprentice-victim pattern.
Professor George Fogle

Professor Fogle teaches the Colonial University course on serial murder and is writing about Daniel Redding. His connection to Emerson and his later death make him a key link between the university suspects and Redding’s prison-based manipulation.
Geoffrey

Geoffrey is Professor Fogle’s teaching assistant, a self-important student who relishes the theatricality of Fogle’s lectures and violent details about Redding. He provides information about Emerson, the class, and the exam video that helps establish alibis.
Bryce Anderson

Bryce is one of Emerson’s classmates in Fogle’s course and project group. Her testimony about Emerson’s group dynamics and missed exam helps Cassie understand the student network surrounding the victim.
Derek

Derek is a student in Emerson’s class group who claims Emerson had a relationship with Professor Fogle. His accusation pushes the investigation toward Fogle before the team learns the student suspects were alibied.
Conrad Mayler

Conrad is a former student who posts crime-scene footage and later uploads the exam video from Fogle’s class. That video proves the entire class was in the auditorium when Emerson died, forcing a major pivot in the investigation.
Director Sterling

Director Sterling is Veronica Sterling’s father and the FBI director overseeing the disputed Naturals program. He distrusts Dean because of Daniel Redding but ultimately accepts outside oversight and the program’s restructuring.
Scarlett Hawkins

Scarlett Hawkins is Judd’s daughter and Agent Sterling’s close friend, killed in the Nightshade case. Her death explains Sterling’s departure from the FBI, Judd’s resentment toward Bureau decisions, and Sterling’s later commitment to protecting the Naturals.
Marie Redding

Marie is Dean’s mother, remembered through his visit to his childhood home. She left Dean, was later found alive, and refused to take him back because he was Daniel Redding’s son, deepening Dean’s fear of being defined by his father.
Lorelai Hobbes

Lorelai is Cassie’s mother, whose presumed murder remains an unresolved wound for Cassie. Memories of her and the Rose Red lipstick intensify Cassie’s fear that killers can still reach into her life.
Agent Locke

Agent Locke is Cassie’s former mentor-turned-killer, whose betrayal continues to haunt Cassie throughout the book. References to Locke’s murders and gifts shape Cassie’s guilt, self-doubt, and Daniel Redding’s later attempts to unsettle her.
Mackenzie McBride

Mackenzie is the kidnapped child rescued at the beginning of the story through the Naturals’ profiling. Her survival gives the team a rare victory and demonstrates why the program matters before the darker Redding case begins.
McBrides’ attorney

The McBrides’ attorney is the precise, deceptive kidnapper whose lies and behavior lead Cassie, Lia, Michael, and Sloane to Mackenzie. His capture validates the team’s combined methods at the start of the book.
Director of National Intelligence

The director of National Intelligence is brought in after Agent Sterling reports the off-book Naturals program. This official imposes external oversight, gives Judd authority as advocate, and permits the teens to consult on active cases under strict limits.

Themes

Jennifer Lynn Barnes’s Killer Instinct is, at its core, a thriller about brilliant young people learning that instinct is powerful—but never free from consequence. The novel repeatedly tests whether profiling can save lives without consuming the profiler.

Trauma as both wound and skill. Each Natural’s gift is rooted in damage: Sloane’s patterning, Lia’s lie detection, Michael’s emotional reading, Cassie’s empathy, and Dean’s intimate knowledge of killers all emerge from unstable childhoods or loss. Dean’s confrontation with Daniel Redding, Cassie’s fixation on her mother’s lipstick, and Sterling’s hidden brand show how the past is not background; it actively shapes perception, fear, and choice.
Control, manipulation, and inheritance. Daniel Redding dominates the book even from prison. His “apprentices” turn murder into a game of exchanged targets, proving that violence can be taught, performed, and ritualized. Yet the novel rejects the idea that Dean must inherit his father’s evil. Redding calls Dean his “finest work,” but Dean’s bonds with Cassie, Lia, and the team become a counter-inheritance: proof that identity is chosen as much as shaped.
The ethics of using children as instruments. Agent Sterling’s arrival forces the Naturals program to face its moral contradictions. The teens save Mackenzie and help stop Webber, but they are also endangered, manipulated, and pushed into active trauma. The conflict between Briggs, Sterling, Judd, and the director asks whether results justify risk—and the ending’s restructuring suggests that protection and purpose must coexist.
Belonging amid fracture. The team’s intimacy is messy: jealousy, secrecy, and romantic tension repeatedly threaten trust. Cassie’s choice between Michael and Dean matters less as a love-triangle beat than as part of a broader pattern: these characters crave connection but fear becoming liabilities. Their celebrations after Mackenzie’s rescue and Christopher’s arrest show how fragile, necessary joy is.
Seeing monsters clearly. The course title “Monsters or Men” echoes throughout the novel. Redding, Webber, Clark, and Christopher are terrifying not because they are inhuman, but because their needs—for power, recognition, love, control—are human drives warped into violence. Cassie’s task is to understand darkness without surrendering to it.

By the end, Killer Instinct argues that insight must be paired with boundaries, and survival with accountability. The Naturals remain gifted, but now their work demands not only brilliance, but care.