As the Shane Gang returns to the 99 caverns from their Eastern adventure, they find Gateway Cavern overrun with slugs. In the Shane Gang's absence, the Shadow Clan took a different approach to protecting the caverns, putting slugs before the needs of people and it's up to Eli and the gang to restore balance.

The Shane Gang takes Tad under their wing, training him to become a great slugslinger with Eli's old blaster. Their training is put to the test when the Gang brings Tad to answer a distress call that leads to a showdown with the Scrap Force and the Shadow Clan.

Tad is missing after the slug-out with the Shadow Clan, so the Gang sets off without him to investigate reports of slugs disappearing. The mystery deepens as the trail of slugs leads straight to Dr. Blakk's old stronghold!

Tad's hypnotic slug Pieper has gone megamorph, his gang of supporters all have Gattler blasters and Tad's control over his new ghouls is stronger than Dr. Blakk's ever was. The Shane Gang are under non-stop ghoul fire as they struggle to put a stop to Tad's plans and the mass ghouling of slugs once and for all.