Thanks to the brave efforts of crown prince Lord British and the hero of the Gradius Army, peace was restored to the watery planet known as Latis. However, that peace was short-lived as the seemingly defeated Salamander Force regained its strength and set out to conquer Latis once more. Meanwhile, the Gradius Army found itself struggling against the Bacterian super weapon known as Dark Force, as the evil empire sought to spread its influence to the far reaches of the galaxy. With no hope of calling upon their former saviors for help, Latis's imperial princess is forced to personally take the fight to the enemy in an upgraded version of her brother's beloved ship, the Lord British MK III fighter craft. She is joined by the Vic Viper Type L, a brand-new ship made with Gradius's technology and Latis's latest scientific advances.