After an evil wizard named Aku conquers his land, Jack is sent away as a young boy to train as a samurai and save his people. When Jack is banished to the bleak future, his physical discipline and stoic nature make him a timeless hero to citizens of all worlds.

Samurai Jack's chief tormenter is a supernatural, shape-shifting beast whose reign of evil has thrust mankind into a realm of hate and darkness. Aku knows Samurai Jack is the only force that can defeat him, so he does everything he can to thwart the displaced warrior.

With his magic sword, machine gun-leg and formidable brogue, the Scotsman is an imposing warrior indeed. At first, Jack and the Scotsman were adversaries, but they have since put their differences aside in the fight against Aku.

From deep within the bowels of the pit of hate, Aku summons Demongo, the Soul Collector, to destroy Samurai Jack. Demongo has the ability to steal the essences of the universe's greatest warriors, but Jack is able to use those very essences to triumph over this foe.