The Lightning Horizon

A mysterious, lightning-charged storm rips through the Edge, tearing Hiccup and Toothless from the Archipelago and dropping them into the high-tech streets of Central City. They cross paths with Team Flash, who are recovering from their grueling victories over Reverse-Flash, Zoom, and Savitar. As the team at S.T.A.R. Labs detects massive amounts of exotic Speed Force energy radiating from Toothless, a new threat emerges: an alliance between a rogue speedster and a villainous dragon hunter faction. Hiccup must combine his mechanical ingenuity and dragon-riding skills with Barry Allen's super-speed to find a way home before both of their worlds collapse under the strain of the colliding timelines.