The ENO’s first opera for children adapts a beloved picture book by Oliver Jeffers into a show aimed at five- to eight-year-olds. They have added not only music, but also a good deal of backstory – including a severe case of flatulence for a silent, but deadly, penguin.

A boy flies a plane and ends up on the moon, having run out of petrol. There he meets a Martian, whose flying saucer has crash-landed. Together they find a way back home – the alien to her blobby father, the boy to his penguin. But the boy is compelled to chatter, while the Martian craves silence. My five-year-old, who sat transfixed through the entire 50 minutes but afterwards pronounced it all “too noisy”, was on the Martian’s side.

Where Joanna Lee’s score is concerned, the noise is a good thing. Propelled by bouncy, angular piano, and with other instruments adding melodic snippets and mischievous flourishes, it doesn’t talk down to its young audience. Rory Mullarkey’s libretto expands the book considerably, and the result is quite wordy. Moreover, he adds four singing Gizmos, who provide sound effects – mostly unnecessary in the Young Vic’s tiny Maria theatre, where even the noise of the boy zipping up his jacket is already clearly audible.

Still, it’s a fun, pacy show, even if it seems a bit unfocused. Katie Mitchell’s direction is slick, Stephen Higgins’s conducting is snappy and Vicki Mortimer’s cut-out designs make it feel as if we are inside the picture book. Victoria Simmonds and Aoife O’Sullivan are lively and communicative as the boy and the Martian. But then there is the penguin, which brings a problem as well as a smile. Devotees of Jeffers will recognise it as the lonely bird who came home with the boy in one of his other books. Now they seem stuck in a dysfunctional relationship, so Jeffers’s message for a younger audience – that friendships, once made, might last forever – is lost.

• Until 23 December. Box office: 020-7922 2922. Venue: Young Vic, London.