T. R. Hendricks writes survival-oriented action thrillers featuring Derek Harrington, a retired Marine Force Recon warrant officer and former SERE instructor whose wilderness skills become essential when he is drawn into operations against a domestic extremist organization.
Hendricks’s bibliography is currently compact and straightforward. Begin with The Instructor, then continue with The Infiltrator. The second novel takes place about a year after the first and directly continues Derek’s conflict with Autumn’s Tithe, so this is a series where publication order matters.
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The Derek Harrington route takes only two books
- Start with The Instructor to meet Derek Harrington, understand his survival school, his financial and family pressures, and see how he first becomes involved with Autumn’s Tithe.
- Continue directly with The Infiltrator, where Derek is now working with the FBI against the organization he encountered in the first novel.
There is no separate prequel, novella, or alternate chronology needed for a first read. The published sequence already follows Derek’s story in the most useful order.
Derek Harrington books in order, with what happens in each
- The Instructor (2024): Retired Marine Force Recon warrant officer and SERE instructor Derek Harrington is struggling to keep his wilderness-survival school alive when a former student offers him $20,000 to train an anonymous private group for thirty days in upstate New York. What looks like a lucrative bushcraft job becomes an undercover FBI operation after Derek realizes his students may be preparing for domestic terrorism.
- The Infiltrator (2024): One year after Derek’s first confrontation with Autumn’s Tithe, he has become an important FBI asset in the effort to destroy the group. Intelligence points toward a final camp in the Kentucky wilderness, while former FBI agent Hannah Kittle, now operating within the extremist organization, prepares for a confrontation that eventually threatens Derek’s family as well as the mission.
Read these consecutively. The second book does not introduce Autumn’s Tithe from scratch. It assumes readers already understand why Derek is involved, what the organization represents, and why several of the returning characters are personally important to him.
The Instructor begins as a wilderness job, not an FBI mission
Derek Harrington is not introduced as a government operative looking for his next assignment. He is a retired Marine trying to make a civilian life work.
His bushcraft school is close to failing financially. He also needs money to help care for his ailing father and support his former wife and their son. That makes the private training offer difficult to refuse even though the clients’ demand for anonymity feels wrong from the beginning.
Why Derek accepts the thirty-day training job
The $20,000 payment is large enough to solve several immediate problems for Derek. His concerns begin growing once the training requests move beyond ordinary wilderness skills.
Instead of teaching campers who simply want to survive outdoors, Derek realizes he may be improving the capabilities of a group preparing for violence. He contacts an FBI connection and becomes an informant inside the very camp he has been hired to train.
Survival training is part of the plot, not background decoration
The Instructor uses shelter, fire, water, food, navigation, fieldcraft, and survival priorities as parts of Derek’s professional identity. His SERE background explains both why the group wants him and why he can function once the situation becomes dangerous.
The novel therefore differs from military thrillers where the wilderness is simply a setting. Derek teaches these skills for a living, and his ability to evaluate what his students are learning helps him recognize that the group’s intentions go beyond ordinary preparedness.
Autumn’s Tithe turns the first book into a domestic-terrorism thriller
The private group Derek agrees to instruct is connected with Autumn’s Tithe, a fringe movement whose members are preparing for violence rather than an ordinary survival exercise.
Derek’s problem becomes unusually difficult because he cannot simply walk away after learning what the group is planning. Doing so could expose him and leave the FBI without someone inside the camp.
The students eventually become Derek’s enemy
The title The Instructor becomes increasingly important as the story develops. Derek has personally improved the field skills of people he may later have to stop.
That creates a different kind of confrontation from fighting an unknown opponent. Derek understands how his students have been trained because he was the person teaching them.
The Infiltrator begins after the FBI has taken the threat seriously
By The Infiltrator, Derek no longer has to persuade federal authorities that Autumn’s Tithe represents a genuine danger. The first novel has already established that.
He is now working at the front of the FBI effort to eliminate the remaining organization. Several successful operations have weakened Autumn’s Tithe, but intelligence suggests one major camp remains in remote Kentucky.
Why The Infiltrator is a direct sequel
The second book is set roughly one year after Derek’s original clash with the extremists. The continuation is explicit rather than thematic.
- Derek is still dealing with Autumn’s Tithe.
- The FBI operation grows directly from the first book.
- Returning characters have changed sides, positions, or responsibilities because of earlier events.
- Derek’s family becomes increasingly vulnerable to people who now know exactly who he is.
Starting with The Infiltrator would reveal the outcome of major elements from The Instructor before the reader sees how Derek became involved.
Hannah Kittle changes the shape of the second novel
Former FBI Special Agent Hannah Kittle becomes an important opposing figure in The Infiltrator. Within Autumn’s Tithe she is known as Sarah, and her position inside the movement gives the novel an internal perspective on the organization Derek is trying to destroy.
Her situation is unstable. The people supporting her no longer have complete confidence in her ability to lead, which creates competing plans inside the group instead of presenting Autumn’s Tithe as one perfectly unified enemy.
Kentucky replaces New York as the main wilderness battleground
The first novel uses upstate New York as the location where Derek enters the extremist training environment. The sequel moves the main operation into remote Kentucky.
That lets Hendricks retain the man-versus-wilderness element without simply repeating the same camp and terrain. Derek’s survival expertise remains relevant, but the mission is now an organized counterterrorism operation rather than an improvised attempt to understand his students.
Derek’s family gives both books stakes beyond the mission
Derek’s father, former wife, and son are established before he ever agrees to the private training assignment. They explain why he needs money and why maintaining a civilian life matters to him.
As Derek becomes more deeply involved with the FBI and Autumn’s Tithe, those relationships also create vulnerabilities. The Infiltrator pushes the conflict closer to the people Derek is trying to protect rather than keeping the danger safely contained in distant wilderness.
Publication order and chronological order are the same
There is currently no complicated Derek Harrington timeline to rearrange.
- The Instructor: Derek first encounters Autumn’s Tithe and becomes an FBI asset.
- The Infiltrator: One year later, he is helping the FBI hunt the surviving organization.
The same order works for a first read, a reread, and a chronological project.
What kind of hero is Derek Harrington?
Derek combines several familiar action-thriller archetypes without fitting perfectly into any one of them. He has a special-operations background, but he is retired. He knows survival, but he is a professional instructor rather than simply an outdoorsman trapped in the wilderness.
He also begins the series with financial obligations, an aging parent, an ex-wife, and a son. Those ordinary pressures distinguish him from protagonists who can disappear into covert missions without affecting anyone at home.
Hendricks’s own military background
T. R. Hendricks served as a U.S. Army captain. His military career included work as a tank platoon leader and later as a military intelligence officer.
He also served as an adviser to the Iraqi Ministry of Interior’s National Information and Intelligence Agency. That background helps explain the books’ combination of tactical action, intelligence work, and concerns about how organizations identify and penetrate extremist networks.
A survival-thriller route through both books
- The Instructor: Start with Derek teaching survival skills and gradually realizing the people paying him may be preparing for terrorism.
- The Infiltrator: Continue once those students have become part of an organization Derek is actively helping the FBI dismantle.
Because only two novels are currently published, there is little benefit in sampling out of order. Reading both gives the complete Derek Harrington arc available so far.
Latest T. R. Hendricks book
As of September 9, 2026, The Infiltrator remains the latest published Derek Harrington novel.
The principal publisher series catalog lists two Derek Harrington novels: The Instructor and The Infiltrator. No third released novel needs to be added to the sequence at this update.
Questions about the Derek Harrington series
What is the first T. R. Hendricks book?
The Instructor is Hendricks’s debut novel and the first Derek Harrington thriller.
How many Derek Harrington books are there?
There are two published novels as of this update: The Instructor and The Infiltrator.
Do I need to read The Instructor before The Infiltrator?
Yes. The Infiltrator is a direct continuation of Derek’s conflict with Autumn’s Tithe and takes place about one year after the first book.
Is Derek Harrington still a Marine?
No. He is introduced as a retired Marine Force Recon warrant officer and former SERE instructor who now teaches civilian wilderness survival.
What is Autumn’s Tithe?
Autumn’s Tithe is the domestic extremist organization that connects the two Derek Harrington novels. Derek first encounters its members while being paid to train a private group in The Instructor.
Is The Infiltrator a standalone?
Its central wilderness operation can be followed on its own, but it is not the recommended starting point because the principal enemy and Derek’s FBI involvement come directly from The Instructor.
Are there any T. R. Hendricks standalones?
The principal published fiction catalog currently consists of the two Derek Harrington novels rather than a separate group of standalones.
The complete T. R. Hendricks reading plan
Read The Instructor first. It explains Derek’s military background, survival business, family obligations, and the private training job that places him inside Autumn’s Tithe.
Then read The Infiltrator. Derek has become an FBI asset, the surviving extremist network has moved into a new phase, and his former students are no longer simply suspicious clients but people he may have to fight.
With only two books and a direct one-year progression between them, this is one of the simplest action-thriller series to keep in order.
Frank is the editor of BookSeries.blog, focusing on publication order, chronological timelines, and spoiler-free reading guides for book series and fictional universes.