Mary Norton's much-loved novel The Borrowers, about the small people who live under the floorboards in the homes of "human beans" and "borrow" whatever they need, is the inspiration for this gentle but imaginative adventure for six to 11-year-olds that takes place all around the BAC building. Send your children off into the supervised care of the Borrowers International Network (Bin for short) and they will come back with tales of paperclips used as coat hangers, teaspoon guitars, the Borrower form of crazy golf known as Bolf – and the time 8,000 Borrowers attended a concert for the super-group, Take This.

This is an understated piece, full of delicate touches. Drawing from the conventions of promenade and immersive theatre, The Great Escape scrounges inventively from Kazuko Hohki's previous 2004 piece for adults, Evidence for the Existence of Borrowers: the children are sent off on a quest around the building, playing Borrower I Spy, examining Borrower cultural artefacts and helping a Borrower called Bob escape the clutches of the KBD (Keep Borrowers Down). The daring balloon-powered escape is a moment of blissful spectacle on the steps of the old town hall.

From its spoof horror film in the "binema", where the terrible health hazards faced by Borrowers are demonstrated, to the white coats and glasses we all wear as scientific investigators, this low-key show relies less on the storytelling tradition of most children's theatre and more on game playing, and on the creation of its own complete and completely daffy world. Your children may emerge not entirely sure what it is they've seen and experienced, but they are likely to remember it for years.