June 11 (Bloomberg) -- A spy doubling as a Barings banker, a courtesan posing as a countess and an arms dealer manipulating stock markets propel the plot of Iain Pears’s sprawling tripartite mystery, “Stone’s Fall.”

Yet the most compelling protagonist in this novel is money.

Pears is best known for “An Instance of the Fingerpost,” a bestseller that meshed mathematics and early medicine with revolutionary politics in Restoration England. In “Stone’s Fall,” he tells the story of late 19th- to early 20th-century capitalism through the rise and fall of one man, John Stone.

Being Pears, he starts with the fall and works his way back in time to the rise.

The place is London, the year 1909. Stone, an arms maker and financier with the title of Lord Ravenscliff, is found dead, having tumbled from a window of his study. Stone’s last will and testament contains a surprise bequest of 250,000 pounds to a child who nobody -- least of all Elizabeth, his wife of almost 20 years -- knew existed. So she hires a crime reporter, Matthew Braddock, to track down the heir.

Braddock disguises his investigation as research for a biography about Stone. As he narrates the first part of the novel, the journalist eases the lay reader into the world of finance through his own clumsy attempts at understanding the figures that swim before his eyes.

“Clearly this capitalism was a more complicated beast than I had thought,” he groans.

Though at first amusing, his incomprehension soon grows annoying. Braddock is such a nebbish that it never seems credible that he will get to the bottom of the mystery.

Two Memoirs

Almost half a century after he abandons his inquiries, Braddock receives a package containing two bundles of papers -- memoirs that form the second and third parts of the book. One was written by a man named Henry Cort, the other by Stone.

Cort turns out to be a Barings bank employee who doubled as a spy. Working for the British government (and freelancing for others) he became a broker of military intelligence who in the 1880s added a shrewd young streetwalker in Calais to his payroll of informants. When he next sees her, she’s passing herself off as a Hungarian countess -- Elizabeth Hadik-Barkoczy von Futak uns Szala -- and moving in lofty social circles. She captivates the rich and powerful, including Stone.

Cort’s big moment comes when he gets wind of a Franco- Russian plot to oust London as the world’s financial capital by engineering a run on the Bank of England. Stone proves vital in averting the crisis and -- no surprise given his access to inside information -- emerges from the rescue all the richer.

Torpedo Patent

In the third stretch of the book, Stone’s memoirs take us even further back in time. The son of an English country curate and his Spanish wife, Stone comes into a moderate inheritance in the 1860s and sets forth on a Grand Tour of Europe.

In Venice, he stumbles on a Scottish inventor who has inadvertently sold his patent for a new weapon -- the torpedo -- to loan sharks. Stone pays off the debt, acquiring the technology for just 273 pounds, and sets up the Gosport Torpedo Company.

Before the riddles of Stone’s death and secret child can be resolved, the narrative slithers through a tangle of melodramatic twists, transporting us from anarchist meetings and shipyards to Parisian salons and seances. Blackmail and intrigue figure in the plot, as do murder, explosions and forbidden love.

Hazy Motivation

For all its abundance of action, the novel plods under the weight of Pears’s research. While you’ll learn how much coal a fleet of 19th-century battleships consumed in a month (45,000 tons), Stone’s motivation remains hazy and key themes languish.

Among them is the notion that it’s politics that corrupts money, rather than money that corrupts politics. The view is advanced by various characters, from a European banker to Stone.

It’s an argument of prescient topicality, and a less diffuse narrative might have permitted a more rewarding exploration. All the same, Pears deserves recognition for awakening to the reality that most novelists miss: Finance impinges far more powerfully on daily life than politics.

“Stone’s Fall” is from Cape in the U.K. and from Spiegel & Grau in the U.S. (608 pages, 18.99 pounds, $27.95).

(Hephzibah Anderson is a critic for Bloomberg News. The opinions expressed are her own.)

To contact the writer on the story: Hephzibah Anderson in London at hephzibah_anderson@hotmail.com.

Last Updated: June 10, 2009 19:00 EDT