Six-Gun Gorilla: Long Days of Vengeance is the story of Kumba, an intelligent, sharp-shooting circus gorilla who blazes a trail across the Old West in search of the outlaws who murdered the man who raised him. Along the way he joins forces with his human sister, the only one who truly understands him, and Union spy Giuliano Schmidt. Together they hunt down the killers, only to find themselves uncovering a much greater threat: a munitions tycoon with a sinister plan to prolong the Civil War.