Although his popularity is eclipsed by Rembrandt today, Peter Paul Rubens was revered by his contemporaries as the greatest painter of his era, if not of all history. His undeniable artistic genius, bolstered by a modest disposition and a reputation as a man of tact and discretion, made him a favorite among monarchs and political leaders across Europe--and gave him the perfect cover for the clandestine activities that shaped the landscape of seventeenth-century politics.

In Master of Shadows, Mark Lamster brilliantly recreates the culture, religious conflicts, and political...