There are moments to savour in Complicite's first ever children's show – co-produced with the Bristol Old Vic, Liverpool Everyman and Playhouse, Oxford Playhouse, Wales Millennium Centre and Warwick Arts Centre – but the show is too long and the narrative too untidy.

Adetomiwa Edun in Lionboy
Adetomiwa Edun in Lionboy
Annabel Arden's production, designed by Jon Bausor and Jean Chan, with lighting by Tim Mitchell, is based on a trilogy of books by Zizou Corder (alias Louisa Young and her daughter Isabel Adomakoh Young) which chart the adventures of Charlie Ashanti across seas and continents in search of his scientist parents – who have been abducted by the "corporacy" for being too humane.

Charlie (winningly played by Adetomiwa Edun) is similarly decent, and his main task, en route, is to release a pride of lions back into the wild. He is hired by a boat-load of eccentric Parisian circus performers as their monkey pooper-scooper and realises his full "cat-like" potential in the lions' den in Morocco before breaching the evil headquarters in a sci-fi showdown to save all the animals.

Needless to say, all medical research done on animals is a bad thing in this show, and the children in the audience who've benefited from it all their young lives are on their feet roaring and cheering like mad. Making money out of these medicines is obviously wicked, too, but Charlie's parents have come up with a pure cure for asthma.

Various threads in the storyline – the exact sense of location, the rivalry with a top-hatted bad boy in smart trainers, let alone the morality of medical research and the fate of the parents – are tangled beyond comprehension then drowned out in noise.

It's typical of the show that a lion's head is beautifully conjured in a shadow play by three of the actors; but then the lions themselves fail to live up to this representation. The best moment is when a shower of eels (black hose) is thrown into the audience. And there's some great physical movement from Lisa Kerr as a circus aerialist and lizard-like chameleon who helps Charlie penetrate the headquarters.

The cast of eight also includes Femi Elufowoju Jr (founding director of Tiata Fahodzi) and Victoria Gould as various elders and worthies, including a bearded lady; Clive Mendus as Sergei from Wigan (genetically modified by the "corporacy" to give you allergies and asthma); and Stephen Hiscock on a fine array of musical instruments.

But I don't think the show poses any great threat to either The Lion King or any journeyman Jungle Book. And its pious tub-thumping is as off-putting and as sentimental as Roald Dahl's in Fantastic Mr Fox.