Prohibition drifts into northern Vermont like the thick fog that occasionally envelops its major waterway, Lake Champlain. It is recklessly disregarded, dividing the nation and its family units, but offers economic opportunity for Armand Dubuc, a veteran of WWI returning home, finding no work but willing to risk the dangers of rumrunning on this lucrative water route.

Armand pursues a love affair with Cosette, a comely French nurse who saved his life during the battle of Chateau-Thierry. His boating cunning eventually is overcome by the U.S. Boat Patrol-the Prohibition enforcement arm on the lake-and he faces prosecution in federal court. There with the skill of his lawyer, who himself has a challenging conflict within his own family over the 18th Amendment, Prohibition itself is put on trial, the jury is led to vote its conscience, which forces the judge-mired in his own misdeeds-to take action that shakes the fabric of the community. Justice in an unexpected way is ultimately served.