Rule Of Existence by Dan Spencer

In the final days of World War One, a deadly epidemic grips America, killing more people than the war. As the disease spreads, Dr. Burton Reinhardt learns that mysterious circumstances have befallen his family. With that, an adventure begins. The influenza outbreak of 1918 sets off this novel about an unorthodox physician's search for his missing daughter, the lawman intent on arresting him for a questionable crime, and the doctor's compulsion to put his family above all else, even his sworn duties.