The more children you bring along to this new family show – the latest co-production from the Globe theatre and Splendid Productions – the more fun you’ll have. It’s ostensibly about a 12-year-old school boy, Cass, who is struggling with his doubts and fears and considering reining in his imagination altogether. However, what makes this stubbornly ambitious production so special is the gleeful sense of playfulness it ignites in the young audience, as well as the parents watching alongside them.

The story unfolds in young Cass’s imagination; a place populated by a host of cracking make-believe characters. There’s classical Shakespearean actor Sarah, played with a twinkling sense of pomposity by Kerry Frampton (also a co-writer on the show). Then there’s Tanvi Virmani’s plucky Cobweb - a minor Shakespearean character who has stuck around in Cass’s mind thanks to a brilliant production of A Midsummer Night’s Dream. Finally we have Zachary Willis’s Big Guy, one of Cass’s favourite TV characters, who spends most of his time enacting very silly and very funny play-fights.

Much of the show is spent larking around with the gang, while Cass (Kyle Ndukuba) sulks moodily on the edges of the action. Together we sail the seas, summon up huge swaying forests and battle monsters, all directed with a lovely light touch from Lucy Cuthbertson. As Cass’s anxiety grows stronger, Rose Revitt’s design sparks into thrilling life. Actors are swallowed up by trap doors, smoke billows through the theatre and a huge, looming shadow-puppet threatens to engulf us all.

It’s all effortlessly captivating until the second half, when things get a touch too meta-theatrical and ultimately pretty confusing. There’s a complicated strand about the importance of messiness and fear, and a slightly buried idea about just how boring our lives, stories and Shakespeare’s plays would be without a little bit of chaos. It’s a lot to fold in to a loosely constructed family show, and the younger children’s eyes begin to glaze over. But it isn’t long before the fun begins again and we’re reviving Cass’s friends with some magic dust, singing and tickling – all thanks to suggestions happily bellowed out from the audience.