Quick recap
Hiccup's academy goes from school to Berk's defense force. The riders face Dagur the Deranged, chief of the Berserkers, who wants to rule the archipelago and capture a Night Fury. Alvin is still around and even teams up with Dagur. Along the way come new dragons, like a giant tunneling dragon that attacks the island, and Heather, a girl who wins the gang over but is hiding something. The season ends with Berk still standing after the Berserkers' biggest attack.
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