Witnessing unusual activity in the Kingdom of Webs from his cauldron, Mumm-Ra summons Nemesis to explain this phenomenon to him. The force of darkness informs Mumm-Ra that the Kingdom of Webs has a newly hatched queen called Spidera. Mumm-Ra then transforms into the tiny Diamondfly in order to lure the ThunderCats into Spidera's web of rage.Outside Cats Lair, Lion-O is lazing in the grass when he hears cries for help. When he goes to investigate, the Diamondfly mesmerizes Lion-O into a trance and starts leading him towards Spidera's lair. When Snarf, who had just emerged from Cats Lair, notices the Claw Shield and the Sword of Omens lying unguarded, he knows something is terribly wrong. He picks up the two items and goes off in search of Lion-O. Snarf finds Lion-O deep in the forest, still under the Diamondfly's spell, but manages to snap him out of his trance. Back in his senses, Lion-O uses the Sword of Omens to expose the Diamondfly for who she really is, Mumm-Ra. Unfortunately, Snarf gets caught by a spider who drags him underground. Lion-O goes after Snarf and finds himself in the Kingdom of Web where his beloved nursemaid has been trapped in a cocoon in a giant web.As Lion-O tries to free Snarf, Spidera appears and Lion-O immediately summons the other ThunderCats. While waiting for his friends to arrive, Lion-O valiantly battles Spidera but eventually gets the Sword of Omens knocked out of his hand. Spidera then flings Lion-O into one of her giant webs where he becomes stuck and unable to move.At that moment, the ThunderCats crash into Spidera's lair in the ThunderTank. Panthro, Cheetara and Tygra all attack Spidera while at the same time trying to get the Sword of Omens to Lion-O. However, Spider proves to be too strong for them and one by one they all end up being caught in her steel-like webs. Tygra manages to throw the sword to Snarf who catches it with his tail and flings it to Lion-O.Lion-O grabs the sword and frees himself from the web. Seeing their lord in action gives all the other ThunderCats the power to break free of their web bindings. With a renewed vigor, the ThunderCats attack Spidera again, this time succeeding in defeating her.