Written by Laurence James and John Harvey, the adventures of Caleb Thorn take place during the American Civil War ... a conflict that becomes decidedly personal after Thorn's beloved mother is killed by Rebel artillery fire. When Thorn subsequently falls foul of his commanding officer -- whose son he killed in a duel -- Thorn is given a stark choice ... spend the rest of his days languishing in a stockade, or take a bunch of condemned men on a whole series of missions, any one of which could result in their death ....