Will Shane is the beacon of justice in Slugterra. But when his enemy, Dr. Blakk, uses a corrupted slug in a duel, Will disappears. As he is sucked into the portal the slug created, Will asks Burpy to find his son Eli and "give him the letter." Years later, fifteen-year-old Eli enters the underground world of Slugterra for the first time. From his father's hideout, he gets gear, a blaster, and a Mecha Beast, which he names "Lucky." He meets Pronto, a proud and knowledgeable molenoid tracker