A couple of imaginative flashes and some quirky talking creatures save this live action kids’ epic from total boredom. But, like its title, this film is mostly bland and semi-forgettable – with scenes more than a little familiar from the fantasy back catalogue, adding no real flavour of its own.

It’s set in 1960s Australia, where Peter (Sam Everingham) is an anxious 12-year-old who’s just moved to a spooky house in the countryside. On the very first night in his new bedroom, the floor rips open, swallowing up Peter and his little sister Verity (Alyla Browne). Their bed careens Goonies-style down tunnels, landing in an underground world inhabited by an army of pangolins (a nice choice for military mammals, with their armour-like scales). The pangolin general greets Peter as a king, just in time to save the land from an evil force. But isn’t Peter just a scared kid in a dressing gown?

So begins an epic journey in which Peter must solve riddles, collect magical stones and find his inner brave. But somehow even this quest fails to inject much energy into the movie, which feels weirdly without atmosphere. It’s also fairly talky, exposition dragging several scenes into dullness. Still, there are flashes of invention, like the moment Peter arrives at a fort guarded by massive stone hands straight out of Monty Python. Peter challenges the hands to a game of rock-paper-scissors.

The Secret Kingdom is a film with well-intended things to say about childhood anxiety and fear, but lacks much spark or fun. Peter’s sister Verity is also fairly annoying (for reasons that only become clear in a twist at the end, she’s a complete goody two-shoes). Still, for under-eights, too young for Harry Potter or Narnia, this might work as gateway fantasy. I was irrationally irritated by Peter repeatedly using the modern jargon phrase“think outside the box” – in the 60s! Little ones won’t be so bothered.

• The Secret Kingdom is released on 21 July in UK cinemas.