Whatever happened to Brenton Thwaites? For some reason that crossed my mind as this thoroughly entertaining fantasy adventure gets off to a rollicking start and keeps going. Now if you are the “Hagar”-esque Viking chief (Gerard Butler) expecting your son to take over as fearless dragon-chaser after you, why would you call him “Hiccup”? Might as well call him “Buttercup”? Anyway, that hapless lad (Mason Thames) maybe isn’t the most adept on the muscle front but cerebrally he has something of the Leonardo Da Vinci to him as he determines to set about devising a weapon that will tackle the most f...