Based on the book by Cressida Cowell, the 2010 computer-animated adventure How To Train Your Dragon soared tantalisingly close to perfection.

Chris Sanders and Dean DeBlois' brilliantly executed story of one boy's remarkable friendship with a supposedly fearsome dragon was deeply touching, distinguished by richly detailed visuals and an intelligent script.

The sequel, directed solely by DeBlois, expands the narrative arcs of the characters, testing their mettle in the aftermath of tragedy and conflict.

Boys cross the rubicon to manhood, parents make selfless sacrifices to protect their brood and evil poisons an innocent heart.

As a wise woman in the film proclaims, "Good dragons under the control of bad people do bad things".

Five years have passed since Hiccup (voiced by Jay Baruchel) befriended Toothless and the inhabitants of the village of Berk now live in harmony with the dragons.

Hiccup's father Stoick the Vast (Gerard Butler) continues to preside over the people.

He hopes Hiccup will accept his destiny as the next tribal chief but the boy prefers to soar through the clouds astride his trusty Night Fury.

During a regular sortie with Toothless, Hiccup stumbles upon a lost world of rescued dragons and a valiant rider named Valka (Cate Blanchett), who turns out to be a long-lost face from the past.

"It's not everyday you find out your mother is some kind of crazy, feral, vigilante dragon lady!" whoops Hiccup.

A tearful family reunion with Stoick is cut short by diabolical dragon hunter Drago Bludvist (Djimon Hounsou), who storms this lost world and takes control of the majestic fire-breathing creatures using a gargantuan Alpha dragon.

World domination beckons and all that stands in Drago's way are Hiccup, Toothless and the boy's plucky friends Astrid (America Ferrara), Fishlegs (Christopher Mintz-Plasse), Snotlout (Jonah Hill) and the twins Ruffnut (Kristen Wiig) and Tuffnut (TJ Miller).

In almost every aspect, How To Train Your Dragon 2 matches its polished predecessor... except one.

The addition of Oscar winner Blanchett to the vocal fold is a calamitous misjudgement.
From the outset, the Australian actress is engaged in a futile tug-of-war with her Scottish accent that initially roams the British Isles and eventually strays across the entire Commonwealth.

Her verbal strangulations are horribly distracting and undermine some of the film's most emotionally charged moments of reconciliation and remembrance.

For his part, writer-director DeBlois charts a breathless course between drama, action and comedy, the latter delivered with scenery-chewing gusto by Craig Ferguson as Stoick's best friend Gobber the Belch.

"[Valka's] meatballs could kill more beasts than a battle axe. I still got a few knocking around in here!" he grimaces, pointing to his belly.

Flying sequences deliver a vertiginous thrill, especially in 3D, including a couple of death-defying battles that slalom and swoop at dizzying speed.

Blanchett aside, lightning nearly strikes twice.