Through the darkness the man moved from tree to tree, working his way toward the large house. The nineteenth-century estate, forty miles south of Hamburg, Germany, spanned one hundred and twelve acres of beautiful rolling forest and farmland and was designed after the Grand Trianon at Versailles in France. It had been commissioned by Heinrich Hagenmiller in 1872 to win further favor with William I of Prussia, the newly crowned German emperor. Portions of it had been sold off over the years as it became too expensive to maintain so much land.
The man walking silently through the woods had already studied hundreds of...