TROLLS. Voices of Anna Kendrick, Justin Timberlake, Zooey Deschanel, Russell Brand, James Corden, Gwen Stefani. Directed by Mike Mitchell, Walt Dohrn. 92 minutes. Rated G (Very mild crude humour, some scenes may scare very young children).

Unrelentingly bright and poppy plus loaded with celebrity voices and factory-produced covers of popular songs, ‘Trolls’ is entertainment churned out by the cynical of Hollywood machines. Despite this, about half of its runtime is extremely enjoyable. The other half isn’t bad, it just feels like they took a small idea designed to flesh out the story way too far. Like its titular trolls, the movie could do with a haircut, but it’s surprisingly resistant to scrutiny.

In the prologue, Troll Princess Poppy (Anna Kendrick, wonderfully bright and bringing her fantastic singing voice) explains through the medium of aggressively sparkly scrapbooking how the Trolls’ idyllic colony came to pass. Years ago, their deliriously joyful people lived in captivity under the rule of the miserable Bergens. This fate sounds bearable, but each year, come the holiday of Trollstice, the Bergens would eat Trolls, the only way they could ever experience happiness. On the Trollstice that the Bergen Prince Gristle was to taste his first happiness, the Troll King Peppy (Jeffrey Tambor) led a daring escape, springing his people to freedom. The Bergen Chef in charge of the Trolls (Christine Baranski) was banished for her error, and the Bergens went about their miserable life while the Trolls made a new life deep in the woods.

There is only one Troll who does not share Poppy’s pep for life - Branch (Justin Timberlake), who would rather spend his days gathering supplies for his doomsday-prepper-esque bunker than singing, dancing and hugging with the rest of his species. Timberlake is a tough sell as a sad sack, but his golden pipes come into play later. It’s clear that we’ll eventually get his tragic backstory, but for now he’s just the single yin to their overwhelming yang. Just to get the narrative moving, the fireworks of an enormous party thrown by Poppy et al. attract the attention of the Bergen Chef, who grabs a handful of them to take back to Bergen Town. Poppy convinces Branch to come with her to save them, and the pair set off on the Chef’s trail to track down their friends.

Up to this point it’s a fun movie. The animation is rich with detail, from the felt-like fuzz that bedecks almost every surface, to the finely wrought hair on the Trolls’ heads, which they can grow and change the shape and colour of at will. The songs, executive produced by pop megastar Justin Timberlake and featuring names like Gwen Stefani, are aggressively catchy. They smack of just how they’ve been pieced together my musical scientists in some secret laboratory to ensure that they drill into your brain and never leave. I wanted to hold this against them, but truth be told, a catchy tune is a catchy tune. An early example is their cover of Junior Senior’s ‘Move Your Feet’, where the key lyrics have been slightly edited to ‘Everybody, move your hair and feel united!’ Not exactly Shakespeare, but it plastered a guilty grin on my face. The opening act whizzes past in a blur of rainbows and glitter.

Once Branch and Poppy infiltrate Bergen Town, the plot gets convoluted by the addition of Bergen scullery maid Bridget (Zooey Deschanel), who burns with unrequited love for the now-King Gristle (Christopher Mintz-Plasse). Getting Bridget and Gristle together somehow becomes an important goal for Poppy, and the story goes a little off the rails and gets a little dull as it basically apes the plot of ‘Cinderella’ (replacing the talking mice with Trolls). Tough to believe that ‘dull’ could be used to describe this explosion in a confectionary shop, but demoting what makes the film so bright and fun and, most importantly, unique (its Troll protagonists) leads to reduced returns. It’s a total mystery, but somehow the already short 92-minute runtime feels overlong while this subplot plays out. It brings it back on track for the last 15 minutes, but a more Troll-centric flick would have been better.

Underneath Poppy and Branch’s quest to save the Trolls and teach the Bergens that happiness is within reach (without gobbling down a Troll or two), there’s a curious message. It’s that everyone has happiness inside them, but some will need the help of others to unlock it. I’ve seen other reviewers take offence to this, construing it as a suggestion that sad people are inherently broken. I disagree with this conception, and I think that the script from Jonathan Aibel and Glenn Berger (based on a story by Erica Rivinoja) clearly conveys its message without denigrating the experience of people suffering from depression. It’s a nice message too, encouraging us to reach out to those around us who seem to be having a tough time. In Branch’s case, this persistent offering of assistance does eventually pay off.

A film based on the very kitsch and fairly shallow Troll toys appeared to many to be an extremely transparent cash grab. This is not entirely the case. At its best, it’s a blast. At its worst, it’s a little tiring. But as the Trolls would say, let’s focus on the positives.

Callum Ryan is an associate of the Australian Catholic Office for Film & Broadcasting.

Out December 1.

20th Century Fox.