When people think of Peter Paul Rubens, the 17th-century Flemish painter, they probably conjure up images of rosy-cheeked, buxom women, proud courtiers, and grand historical scenes. In “Master of Shadows: The Secret Diplomatic Career of Peter Paul Rubens,” Mark Lamster does nothing to dispel that familiar impression but a great deal to modify it.

In addition to being the foremost artist of his day, Rubens, it turns out, was a top-notch spy, shuttling between Flanders and Spain, England, and France on behalf of his Queen Isabella, in the seemingly impossible task of sorting out the baroque intricacies of the religious and political conflicts of the day. Among the cast of characters here are Cardinal Richelieu, Britain’s James I and Charles I, King Philip of Spain, and assorted Hapsburgs and functionaries from the Holy Roman Empire.

These were the years when Spain was a formidable power and controlled the Low Countries, including Rubens’ Flanders, in what is today Belgium. But these were the years when the Dutch were in rebellion; caught between a Protestant Netherlands and the military might of Catholic Spain, Flanders was in a prolonged and debilitating economic stagnation. With Antwerp, where Rubens was raised, blockaded by the Dutch, that once thriving city withered as the years passed. Although the Spanish allowed Flanders a degree of autonomy, the state remained a kind of no-man’s land caught between mighty opposites. The stakes were high, as the Netherlands and Spain competed in Europe, but also in the Americas and Asia. England supported the Dutch, and the French were occasionally in league with Spain. Although some of the royals among whom he carried coded messages balked at the idea of dealing with a mere artist, there’s little question that most considered Rubens a trusted, discreet diplomat, a celebrity who was also willing to sell paintings or antiquities from his own collections (Rubens was “always a good negotiator”), and to advise nobles on this or that aspect of collecting. It’s difficult to separate his work as artist from his work as spy, insofar as the two were so entwined. It was his fame as an artist and his ardor as a citizen that brought him to the Queen’s notice in the first place, and then it was “painting that gave Rubens the perfect cover for clandestine work.”

It didn’t hurt any that Rubens, “tall and handsome, was the charismatic center of any room he entered.” He was an acute thinker who liked being admired and who “actively promoted . . . fascination with his genius.”

Rubens became quite wealthy, and had the good sense to convert money into real estate (his “success as a capitalist was something extraordinary”), eventually enabling him to design and build a grand house. His great talent as a painter was complemented by a genius for diplomacy, as Lamster’s book makes crystal clear, and those two strangely enmeshed abilities made him sought after and admired.

Tony Lewis ( antjlewis@yahoo.com) is a frequent reviewer in Padanaram.

MASTER OF SHADOWS: The Secret Diplomatic Career of the Painter

Peter Paul Rubens,

by Mark Lamster.

Nan A. Talese/Doubleday. 316 pages. $29.95.