A few years into the American Civil War, mysterious events began occurring and they caused the North and South to put aside their differences and unite once more to battle the common threat. However, the might of their newly united armies was not enough to combat things that were once thought to be merely myth and they were forced to rely on men and women who had unusual powers and who were just as mysterious as the creatures that they were fighting. These people were viewed as a necessary evil and they came to be called Spellslingers. Most were little better than mercenaries and bounty hunters, but no one could argue with their effectiveness when it came to dealing with things beyond the comprehension of mere mortals.
Over two decades after the end of the Civil War, a pair of Slingers named Jacob and Nathaniel Kreed are made unwilling participants in a plot that has the potential to bring about the end of humanity. Together with a mercenary and a female Slinger, and armed with only their weapons and their special abilities, they travel the southern United States and part of Central America in search of answers and a way to save a world filled with people who hate and fear them. They all know that whether they win or lose, nothing will ever be the same.