Jake uses a painting to find a royal emerald stolen by a convict, the painter of the portrait, in 1886. The painting leads him to a tunnel under the Hofburg Palace filled with plaster models of monuments. Jake must contend with several other crooks who are also after the emerald.
The story of Jake Webster, an American expatriate in Vienna who was the operator of Jake's Bar & Grill, an American-style establishment near the scenic heart of the city. In fact, the business was a cover for Jake's actual reason for being in Vienna. He was involved in tracking down various spies and international criminals at the behest of U.S. intelligence, which apparently held something against him which, if disclosed, would have resulted in his being deported from Austria and apparently then incarcerated in the United States. Jake's liaison with U.S. intelligence was a Major Caldwell.