One of the first lessons taught in elementary creative writing classes is to write about what you know.

Better advice would be to write about what you can fake. Creative writing classes, by definition, are about fiction — you know, making up stories, or, as Lawrence Block stated it, telling lies for fun and profit.

A way to accomplish the not-so-easy task of faking it, of making readers believe you actually know what you’re writing about, is to do research. The mark of the amateur is to then fill a novel with everything he learned; the professional knows what he needs to know but doesn’t jam the entire encyclopedia down the reader’s throat. Slip in bits and pieces, on a need-to-know basis, and you’ve got something: The author looks really smart, the reader is delighted to learn arcana unknown previously, and the plot whips along wonderfully without the burden of a treatise delivered while the heroine hangs from the window ledge.

The evidently uncontrollable desire to display his research skills and erudition is the only flaw in Colin Harrison’s otherwise marvelous thriller, “The Finder” (Farrar, Straus & Giroux, 336 pages, $25).

The horrific murder of a couple of innocent Mexican girls in the first chapter, told in sparing, precise, yet evocative prose, will haunt the reader throughout the remainder of the book and beyond. The sequence is both original and creative, yet creepily plausible and realistic. Not to over-describe it, since it screams for sensitivity and understatement in the telling, but the fact is that they are locked in their car and drowned when a truckload of human excrement is piped through its sunroof.

Unwitting elements of a giant scam, the girls worked for an office-cleaning company, gathering the vast quantities of paper that are the residue of high-stakes negotiations and deals: the memos, confidential interoffice notes, reports, and contracts that usually begin on a computer but are habitually printed out. These documents hold the secrets of huge corporations, and the information they contain may be worth fortunes to those who know what to make of it. They cannot be burned, buried, or recycled — they must be shredded.

Jin Li, the beautiful Chinese woman who oversaw this process, made sure that not all papers were shredded, providing vital information to her brother in China, who made millions from the information. Their biggest score had been at the expense of a pharmaceutical company, Good Pharma.

A billionaire investor with a serious position in that company suddenly finds himself in danger of losing his fortune and plays hardball to try to ensure it doesn’t happen. He wanted a message sent, and the Mexican girls paid with their lives.

Jin Li, who had been with the girls when they were murdered, goes on the run as the thugs connected to Good Pharma’s boss want to learn what she’s been up to, and her former boyfriend, an ex-cop, sets out to find her before they do.

Set in the diverse extremes of New York City life, from the Wall Street titans and their luxurious lifestyles to the tough people who haul the city’s sewage, this outstanding thriller moves from Park Avenue penthouses to gritty streets in neighborhoods at the other end of the financial spectrum.

However, I’m not sure Mr. Harrison needed to provide the full details of a digital prostate exam, performed at a swank cocktail party. If you’ve had one, you know what it’s about. If you haven’t — well, you don’t really want to know.

The same attention to detail is provided when Ray lowers himself into raw sewage. Ew. And the lengthy explanation of certain ways in which the Chinese stock market works, and the methodology for manipulating stock prices, might have been interesting if judiciously woven into the novel. Instead, Mr. Harrison provides colorless essays that drag on for pages and are unnecessary anyway.

On the other hand, maybe Mr. Harrison decided the tutorials were necessary to slow the action, which might otherwise have been unbearably exciting. In that case, he did not entirely succeed, because “The Finder” is still a seriously high-energy thriller.

Mr. Penzler is the proprietor of the Mysterious Bookshop in Manhattan, and the series editor of the annual Best American Mystery Stories. He can be reached at ottopenzler@mysteriousbookshop.com.