Under a clear blue September sky, America's financial center in lower Manhattan became the site of the largest, deadliest terrorist attack in the nation's history. It was September 16, 1920. War veteran Dr. Stratham Younger and his friend Captain James Littlemore of the NYPD are caught on Wall Street on the fateful day of the 1920 bomb blast. With them is Colette Rousseau, a French radiochemist Younger met in the war. A series of inexplicable attacks on Rousseau and a mysterious trail of evidence lead the trio on a thrilling international and psychological journey to uncover the shocking truth behind the bombing.