Appearing on the bestseller lists next to John Grisham and James Patterson, Portlander Phillip Margolin is one of the most popular authors of his genre—the legal thriller. A longtime criminal defense attorney, Margolin applies his professional expertise to his latest thriller set in Portland, Proof Positive (HarperCollins, 320 pages, $25.95).

Amanda Jaffe, the heroine of Margolin's previous books Wild Justice and Ties That Bind, is the defense attorney for Jacob Cohen, a mentally unstable religious fanatic charged with a brutal murder. The case appears fairly straightforward; all evidence points to Cohen. But as Jaffe looks closer, more questions arise around the case, and the two people who may have answers are swiftly silenced by an unknown killer. Jaffe must find the missing evidence that will save her client from death row—before anyone else gets killed.

Forensic expert Bernard Cashman is Margolin's villain. Having tampered with evidence in a number of cases and given false testimony in court, Cashman must kill to keep his secret. Over his career, the criminalist has discovered the power he has in his position: "When the police were certain they knew the guilty party but didn't have enough evidence to convict, Cashman came to the rescue." Margolin's inspiration for Proof Positive came from real-life accounts of criminalists in state and federal crime labs who falsified evidence or gave false testimony. With this unexpected twist and fast-paced plot, Margolin tells a suspenseful story.

Read Proof Positive for sheer entertainment, not for memorable characters or life-changing catharsis. A creative-writing teacher would cringe at how often Margolin disregards the first rule of fiction writing: show, don't tell. Take for example, Margolin's attempt to show a judge's wild side: "In court, she hid her sharp blue eyes behind thick unattractive glasses, wore her long black hair in a bun, and concealed her trim figure beneath her black robes. When she socialized, the judge let her hair down, dressed flamboyantly, and wore contacts." Much of the book is hampered by these uninspired descriptions, which could have been replaced with a single dramatic anecdote.

Margolin's bare style and paper-doll characters do serve the satisfyingly swift pace of his books; there's not much to slow anyone down. The best part is getting caught up in the suspense of whether justice will be served. Plus, the scenes in the Multnomah County courthouse might make jury duty a little more interesting next time.