Duane's decision to set out on his own to join Bragg's army at Tullahoma proves to be a mistake. A rapid chain of events carries him from capture along a snowy road by a renegade band of Union calvary, to near death in blizzard in the mountains of Tennessee, to Lee's Army of Northern Virginia in its winter camp around Fredericksburg. Late winter is a time of reprieve from as the boy joins a company from Alabama. The beginning of spring sees the reopening of warfare in the battle of Chancellorsville.
Across the Valley to Darkness follows Duane as 1863 stretches into summer, the army moves north into Pennsylvania, and the boy finds himself crossing the valley at Gettysburg in a great charge against the Union Center on Cemetery Ridge.