When foreign language teacher Celeste Scott is asked by police to help translate a strange note found on a mummified corpse, she and science teacher Harrison Barrett are drawn into the intriguing history of the Byron Hot Springs Resort. Their present-day mystery alternates with the desperate journey of Baron Leopold von Haas, who flees post-World War I Austria and winds up at the famous resort, a half-a-world away.

Harrison and Celeste uncover a web of clues spanning the gruesome death of Charles the Bold in 1477 France to a covert World War II interrogation center in California. Meanwhile, in order to return to his family, Baron von Haas must reveal his secret to one of the resort’s many fabled guests including Fatty Arbuckle, Lefty O’Doul, and the renowned sugar baron, Adolph Spreckels.

What untold story links it all? The answer can only be found where past meets present, fact meets fiction, and mystery meets romance...
...in the shadow of Diablo.