In construction, a stress fracture is a compromised structural integrity that could cause collapse. Medically, a hairline fracture is caused by repetitive stress or strenuous loads. For psychiatrists, it’s sort of a break in transmission of neurotransmitters that makes patients lose touch with reality. In this psychological thriller, D.P. Lyle knows how to put readers into the minds and motivations of predators and their prey --- and law enforcement officers who untangle webs they use to snare: “A criminal leaves behind not only physical clues...but also fragments of his personality. Not always easy to read, and probably not overly accurate, these clues often reflect motivation.”

Years ago, another Octomom must have given birth to eight D.P. Lyles for the multi-talented California cardiologist to be so prolific and diverse. Author of such thrillers as 2002's DOUBLE BLIND, his nonfiction FORENSICS FOR DUMMIES was nominated for the 2005 Edgar Award and earned Mystery Readers International’s Macavity Award. Dr. Lyle has contributed material for many TV shows, including “Law & Order,” “Monk,” “CSI: Miami” and “Women’s Murder Club.” STRESS FRACTURE introduces the Dub Walker series with psychological intrigue, told in a too-realistic-to-be-fiction thriller.

Dub Walker cut his forensics teeth as a Marines MP and consultant in Quantico and with the FBI’s Behavioral Assessment Unit --- sort of an “NCIS” agent wannabe. Along with detective friend Tommy Tortelli (T-Tommy to friends and readers), Dub investigates horrific murders perpetrated by a psychotic serial killer in Huntsville, Alabama. Dub revisits the building where he consulted with police on particularly gruesome serial murders: “The room hadn’t changed. Same faded yellow walls. Same metal desks and chairs. Same tired coffee maker sat on the same wobbly wooden table. The glass coffee pot was new, but there was always a new pot. Glass had a short life span around here.”

Catching a doodlebug --- “Ugly caterpillar-like creatures with pincer mouths” --- with a blade of grass (those from the South don’t need to ask) is used as an analogy to catch psychopath Brian Kurtz. Way beyond half-mad, Kurtz suffers from post-traumatic stress disorder after experiencing unimaginable situations in Iraq. Identified early on as the perp, this is not so much a whodunit as a whydunit. The “why” involves tormented Kurtz receiving psychiatric treatment from clueless physicians Melvin Wexlar and Bob Hublein at the posh North Alabama Neuropsychiatric Research Institute. From some mysterious source, money flows like the Tennessee River into the country-club-like Institute, adding intrigue about an experimental drug called RU-1193 being injected into Kurtz and other PTSD soldiers. These uncharacteristically greedy doctors care more for money than they do for the well-being of their patients.

Though a scene that tracks the money trail ties loose strings into a knot a little too neatly, Lyle writes the perfect prescription for a psychological thriller. Laws are written to keep the majority honest --- and challenge Dub to circumvent them. He breaks into the Institute to get Kurtz’s medical records before the money-grubbing doctors can destroy them.

Because something doesn’t sit right with him, Dub is as uneasy “as a long-tail cat in a room full of rockers.” After all, his name is Dub, not Dupe. An easy solution to crimes raises red flags. Eye-cringing descriptions of heinous murders that likely can’t be committed by the calm person who phones Dub, to give details about the homicides, wake him before the roosters. Dub uses ex-wife and on-again girlfriend/reporter Claire to bait the mysterious murderer with provocative innuendo during TV interviews as a figurative blade of grass, to catch the diabolical doodlebug. He hears a recording of a murder-in-progress: “The killer’s voice was high pitched, angry. His demon had taken over. Mr. Hyde was out.” The calm voice claiming to be the murderer seemingly has a Jekyll/Hyde thing going on, caused by a controlled substance not controlled nearly enough.

With rock-solid writing, Lyle turns a phrase: “The morning sun silvered the [power] lines that swagged above the tree line. They looked like new guitar strings, waiting to be tightened to the proper key.” Multiple homicides --- and solved crimes --- are compressed into one week, with brief flashbacks, to bring readers up to speed in this bullet-train-paced thriller.