With plans to build an indestructible empire, King Tut goes in search of Nilanium, the world's strongest metal. But with the only known deposit lying directly beneath Wayne Manor, Tut's tunneling soon leads him to the discovery of a lifetime - the Batcave itself. With their secret identities in jeopardy, Batman and Robin race to stop him before his find is leaked to the world.

The Joker is back in Gotham City, this time with his sights set on worldwide domination. He plants rumors of an invasion from outer space, then sets out to gather the Beryllium metal needed to build an actual flying saucer. Batman picks up on his scheme and sends Alfred to check up on a stash of the metal. But when Alfred is mistaken for a mad scientist by the Joker, he is hauled off to the villain's lair along with Batgirl. The Dynamic Duo are on their way when a bomb planted by one of the Joker's henchmen goes off, leaving them unconscious, and their Batcave cut off from the rest of the world.