During the Three Kingdoms period, Cao Cao stands as the last pillar of power preventing the collapse of the Han throne. Emperor Xian, who sits on that throne, cares more about music and poems than his own power.
But behind the Emperor's disinterest, rumors that Cao Cao wants the throne for himself have driven Emperor Xian to plot Cao Cao's assassination, a plan that's been years in the making. An ancient prophecy states that when the four elemental stars align, a new dynasty will arise, and in 221 A.D., they do.
With the weakened government and impending omen, Cao Cao has enemies everywhere, and they all want him dead. Someone has been abducting the children of Cao Cao's dead enemies and training them to be assassins. In 221, they are grown, and sent to infiltrate Bronze Sparrow Tower.
When the four stars align over Bronze Sparrow Tower, the struggle for Cao Cao's life begins.