THE CURIOUS INCIDENT OF THE DOG IN THE NIGHT-TIME

For anyone, and there can be very few, who hasn’t read Mark Haddon’s bestselling The Curious Incident Of The Dog In The Night- Time, it is the story, told in the first person, of Christopher Boone, a boy of 15 years, 3 months and 2 days who has a rat called Toby, is so good at maths that he is determined to sit his A level and confident that he will get an A*. Oh, and he has ‘behavioural problems’.

Simon Stephens has solved the problem of keeping Christopher’s eccentric and idiosyncratic voice while also making it theatrical by having his story turned by his wonderfully caring and clever teacher, Siobhan (Niamh Cusack) into a play to be staged at his special school. He, director Marianne Elliott, and the brilliant Luke Treadaway, who plays Christopher, get right under the boy’s skin; a skin that hates to be touched, so cannot be soothed with a hug; a skin that sweats buckets of anxiety.

Christopher’s mathematical mind is reflected on walls of glowing geometric grids on which are projected random numbers wildly whirling like snow in a blizzard. Twinkling lights conjure the stars in the night sky the boy knows and loves. When Christopher gets upset in the frantic turmoil of Paddington Station, he counts, doubling 2s, to restore order, certainty and safety on his feeling of chaos. Numbers make perfect logical sense to Christopher. People do not.

One of the threads of Christopher’s story concerns his determination to solve the mystery of who killed Wellington, the nextdoor neighbour's dog, and who Christopher discovers dead with a garden fork in his body. The other is even closer to home, but utterly impenetrable for Christopher: the breakdown of his parents’ marriage.

It’s frequently harrowing. Treadaway’s  stiff-limbed Christopher doesn’t make eye contact. He pulls at his fingers and the string of his hoodie. Occasionally, and very reluctantly, he allows his parents to brush his fingertips with theirs for just a fraction of a second as a gesture of his special connection with them. One feels their desperation for physical contact as powerfully as his revulsion of it. There’s a heartbreaking moment when his dad has to undress him – he's exhausted after a fit – and Christopher, helpless as a baby, lets him.

But it has lots of good jokes too. Christopher, who always tells the truth, says that other people at his school are stupid, even stupider than Wellington: ‘Steve probably couldn’t fetch a stick.’ And a final, shamelessly sloppy moment had me metaphorically wagging my tail all the way home.

Until 31 August, Apollo Theatre, 31 Shaftesbury Avenue, London W1: 0844-579 1971, www.apollotheatrelondon.co.uk