Gem Greaves’ set for Running on the Cracks, a joint production by Pilot Theatre and Tron Theatre, consists of a nicely solid front door, with ramps and steps leading to it. In many ways this reflects Katie Posner’s production. The open space on and around the ramps and steps sees the characters take the “running” of the title literally – the opening 15 or so minutes, particularly, is deliberately breathless. The door is key to the play’s meaning. Finlay, the chaotic paper boy, faces the question of what goes on the other side of the letter box. Leo, the 15-year-old runaway, gives up the security of a home because the secret terrors of “behind closed doors” become unbearable.

Andy Arnold’s adaptation of Julia Donaldson’s novel crams around 20 characters (played by 5 actors) into a mere 70 minutes of theatre and sets a hectic pace. Oddly, after the impressionist opening, there is no confusion of character or plot, though Arnold keeps explanation to a minimum. Leo runs away from her creepy Uncle John, but Leo is no ordinary runaway. Leo is short for Leonora – she has been named after the Beethoven heroine by her musician parents, killed in an air disaster – and it also reflects her Chinese name, Liu, given because her father was Chinese, disowned after his unmarried liaison with a Westerner.

So Leo flees from and to – from Bristol to Glasgow, from her uncle to the grandparents she has never known. The characters she encounters in Glasgow form a vivid gallery of drunks, the mentally ill, bureaucrats and folk looking for the next penny. The two who impact most on her are manic depressive Mary, whom she first encounters during an expansive phase, and 13-year-old Finlay, the nicely ineffective youth who sells doughnuts in the Barras market (Leo steals them) and worries about the smelly unresponsive house he delivers papers to (it is, of course, Mary’s).

The cast is uniformly excellent. Jessica Henwick (Leo) and Grant McDonald (Finlay) seem a touch older than stated (the adaptation has added a year in each case to help them out), but are both supremely sympathetic. Henwick blends the terror of a teenager on the run with the poise of a young lady educated at home by artistic parents. McDonald manages the difficult feat of being both irritating and immensely likeable – it’s no surprise that the character, created in love and frustration, is based on Donaldson’s younger son! Gaylie Runciman not only copes with the extremes of Mary, but accommodates the sensible middle-class values of Finlay’s Mum. Suni La’s sequence of roles sees her switching from Glaswegian (her doughnut stall holder especially convincing) to Chinese. And Stephen Clyde sails through eight roles, his Uncle John a model of understated creepiness and the best of his cameos the amiably belligerent newsagent and the Music School jobsworth obsessed with the Data Protection Act.

After York Theatre Royal (until 2 March), Running On the Cracks finishes its tour in Lincolnshire: South Holland Centre, Spalding (5-6 March) and Lincoln Performing Arts Centre (7-8 March).