The Mac, Belfast

The hero of Oliver Jeffers's fiendishly clever and fetchingly illustrated The Incredible Book Eating Boy has a voracious appetite for literature – which is not to say that he enjoys reading the stuff. Instead, he devours books, page by page, becoming instantly smarter with every chewed word. It's as though his metabolism is enchanted; a process known, perhaps, as reader's digest. Jeffers folds that quirky idea in on itself: his original picture book even contains bite marks.

Not every adaptation would be up to the double challenge an adaptation of Jeffers poses: to make a book about books work in another medium, and to find theatrical equivalents for the games he plays with reader. Thankfully, this restlessly inventive co-production between the Mac and Cahoots NI tackles both challenges head on and without apology: "You have seen the pictures! You have read the book!" says a fairground barker in Conor Mitchell's adaptation. "Now sit back and see the real thing!"

The real thing here is part musical, part pop-up book, where Sabine Dargent's set of towering books and vertiginous ladders reveals itself like a conjuring act, as the cast sparkle under Muirne Bloomer's choreography, and Mitchell's musical compositions thrum with memorable tunes and more complicated Kurt Weill-indebted arrangements.

That may sound suspiciously elaborate, as though co-directors Paul Bosco McEneaney and Mitchell are addressing two separate audiences at once. But, like jokes that breezily reference JK Rowling and EL James (and every shade between), their enthusiasms are cunningly well combined.

Such levels also seem quite appropriate. As Stuart Matthews's young Henry discovers, while inhaling spelling books then philosophical tomes, every introduction can be the start of endless discoveries.

His appetite is winningly inspired by Colette Lennon's tempestuous Argentinian school librarian, in the form of a heated tango, but Richard Marx, as a coolly narrating figure, Maestro, comes closer to the show's arch temperament, constantly commentating on the action, interrupting anything vaguely conventional, and leading us to a slightly laboured moral – that real learning takes time.

It's fair to ask if McEneaney and Mitchell have much time for a lesson in patience, given their production becomes almost dizzy with distractions. A series of magic tricks that convey Henry's digestive issues are forgivably overindulged, but sometimes Mitchell's unconventional score strains the capacities of its singers while, at two hours, the show can take as long to relax as Henry does.

Those small points aside, though, this is first-rate and intelligent family entertainment that fully honours its source. It's hard to think of a better endorsement, though, than the rapt little girl who asked her mother, without taking her eyes off the stage, if they could read the book again later.

Until January 1st

Peter Crawley ****