The Web of Shadows concerns the return of the heroic Toa to Metru Nui. There, they find an old enemy has overtaken the great city with the help of Visorak--robotic spiders that can quickly encase anything or anybody in near-indestructible webs. The Toa undergo a bizarre metamorphosis while sealed within strange cocoons, and emerge as clunky-looking machines made up of mismatched parts.