Unable to purchase the formula of the explosive about to be sold to the government by Mallott, the representative of a foreign power orders Le Farge and Gabrielle to obtain it. Gabrielle, posing as Le Farge's sister, easily fascinates Fanshell, Mallott's secretary. The adventuress also meets David, a fisherman, and engages him in a violent flirtation.

An orphan boy from the Kentucky hills joins the Union Army and rescues his adopted family from Morgan's raiders. He learns his real identity when he returns after the war.