Seeing King Serse I's power in serious decline and ambitioning to mount the throne, Artabano, the commander of the royal guards and a powerful official in the Persian court, has murdered the sovereign and is now hoping to sacrifice the rest of the royal family to his design. And so, he accuses Dario, Serses I's eldest son and older brother of Artaserse, of the regicide and persuades the latter to avenge the crime. After Dario's demise, the only thing left wanting is now the death of Artaserse, which Artabano has plotted, but his plans are delayed by a succession of various incidents and in the meantime the treason is revealed.
