The Shane gang interrupts an attack, caused by two of Dr. Blakk's employees Locke and Lode, on a shipment of Fandango slugs which are needed to revive a dying cavern after the native slugs fled out of the blue. While the gang heads to the cavern Eli learns that slug energy powers many, if not all, of Slugterra's caverns. Locke and Lode follow and cause a cave in that results in the gang traveling through Shadow clan territory, which leads to a chase deeper into their territory (thanks to Pronto) and a face off between one of the clan and Eli trying to reason with it. Just as the clan is ready to attack Burpy starts chirping frantically and the Shadow clan lets them pass, leaving Eli to wonder what did Burpy say and why did they listen to only him? After finally reaching the cavern and introduce the Fandangos to their new home, the slugs run away from something and before they could figure it out Locke and Lode make a smashing entrance. Eli and Kord face off against Locke and Lode, while Pronto hunts down the Fandangos and Trixie looks for the source of the slugs fear which is in the bullseye. After beating troublesome duo, Trixie informs the boys that the slugs are running from Dark Water that is seeping out from the cavern's monument so Eli asks Doc if he can handle that much to purify to which he replies with a serious and pumped look. As Doc tries to clean the Dark Water, he begins to lose energy just at that moment Pronto arrives... with 1 Fandango, which Eli says is enough to give Doc a boost and it does! Now the Dark Water is purged and the Fandangos and native slugs finds some new places to roost, the gang wonders how many other caverns are starting to be infected with Dark Water and what ever happened to Locke and Lode. They ran to regroup and question if they should now inform Blakk, just when Shadow Clan arrive and chase them.