In the thrilling sequel to the animated adventure series Slugterra, a new member joins the Shane Gang, Junjie, a master of the ancient art of Slug Fu, who possesses the power to control his slugs from afar. With this newfound skill, Eli and his friends must embark on a perilous journey across The 99 Caverns to find the Legendary Elemental Slugs, five ancient beings whose power could either save or destroy Slugterra. As they navigate treacherous landscapes and battle formidable foes, the Shane Gang uncovers a sinister alliance threatening their world's very existence.