In the darkest corners of the vast universe, ultimate evil lurks. The dark forces led by the god of destruction, Bacterian, are preparing to launch a massive attack against the planet Gradius.

With relentless power, the dark forces threaten to plunge the Universe into all-out war and complete annihilation. Their invasion destroys the defenses of Gradius, while the surrounding planets fall like dominoes. Now, the evil hand of Bacterian reaches the heart of the resistance... the planet Gradius itself.

To face the imminent threat, the United Forces of the Gradius world gather all their warships. Half form a defensive network, and the rest an offensive group. However, they are outnumbered, and the dark forces easily break through their thin defensive line. No fighter survives the massacre...

In a last-ditch effort, the United Forces of Gradius send two strike cruisers previously considered too dangerous for combat missions: The Interdimensional Strike Cruisers VIC VIPER. The cruisers take off towards the heart of darkness to join the battle that will decide the fate of the Universe...