Bad Blood

Bad Blood is the fourth and concluding novel in Jennifer Lynn Barnes’s Naturals series, which follows a group of gifted teens whom the FBI recruits into a clandestine FBI program. Each member possesses an innate, specialized ability for solving crimes: Cassie Hobbes is a profiler, Dean Redding shares her talent, Lia Zhang is a human lie detector, Michael Townsend reads emotions, and Sloane Sheridan is a living encyclopedia of facts and statistics.

The series begins with The Naturals (2013), which follows the team’s formation by the FBI and their initial work in solving cold cases. In the second installment, Killer Instinct (2014), the team (Cassie, Dean, Michael, Lia, and Sloane) transitions from cold cases to active investigations, and they look into unusual murders that mimic those committed by Dean’s father, a notable serial killer who is incarcerated. In the third installment, All In (2015), the team travels to Las Vegas, Nevada, to hunt a serial killer whose methods connect to a complex mathematical pattern. In Bad Blood, their focus shifts to an active threat from a secret society of serial killers. Known as the Masters, this cabal has operated for more than a century, orchestrating ritualistic murders in cycles of nine and timing their killings according to the Fibonacci sequence (an infinite sequence of numbers that occurs in patterns throughout nature).

A central mystery that runs throughout the series concerns the fate of Cassie’s mother, who was presumed murdered years ago but, in the fourth book, is revealed to be alive and held captive by the Masters. She isn’t merely a prisoner but holds the title of the Pythia, a high-ranking figure who judges and sanctions the Masters’ killings. Bad Blood escalates this conflict, moving the Naturals from being the investigators to being the targets. As the book’s tagline states, “The hunters become the hunted” (i), forcing the team to confront the Masters directly to save not only future targets but also themselves.

The series combines the methodological framework of a criminal procedural (a genre that emphasizes the process of evidence collection, forensic analysis, and criminal profiling) with the conventions of the Young Adult (YA) thriller (a genre that gained popularity in the 2010s, often featuring teenage protagonists and coming-of-age themes). Barnes centers the series on the personal histories and emotional conflicts of the Naturals team, while they function like a specialized FBI unit, analyzing crime scenes and developing profiles of their targets. Cassie’s tense prison interview with Daniel Redding in Chapter 1, in which she attempts to draw him into a conversation to extract information, is a classic procedural trope. By merging the YA thriller and criminal procedural genres, Barnes creates protagonists who process personal traumas and navigate relationships through the detached, analytical lens of their investigation work.