Underworld

Underworld is the sixth and final volume of the Dragons: Riders of Berk Comic Books. It was released on September 16, 2015.

The comic also contains a mini-comic at the end related to the events in the main story, called Smeltdown.

Overview
During a routine training exercise, Hiccup and his friends discover a huge, mysterious pit in a forest near Berk. . . They decide to investigate. . . Meanwhile, a number of fishing vessels near Berk have gone missing, so Stoick decides to investigate–and bumps into an old enemy. . . And just how are Hiccup and Stoick’s predicaments linked?