When Phil threatens to shut down D'Angelo's new dragon hospital and ban dragons from ICARIS, D'Angelo and a little Hobgobbler have to change his mind.

While Tom struggles with admitting his feelings for Jun, the pair find themselves trapped inside a giant tree with an anxious colony of Woodchipper dragons.

Thunder must wrangle and lead the Hero Dragons in a desperate attempt to save Tom and the riders from a dangerous new dragon, The Glass Caster.