Janina David was nine years old when the Nazis invaded Poland. Within a year, she and her formerly prosperous Jewish family were facing starvation in the Warsaw ghetto.
The Kosh's promenade performance piece, inspired by David's memoir, conveys some of that sense of disorientation. You never know quite where to look, or even where to stand so you don't get knocked over by the march of history and raggle-taggle humanity being swept this way and that.
A Square of Sky is a show of considerable ambition, using film, projections and installations as well as music and live action that crosses the boundaries of drama and dance. It takes a while to get into its stride. The first 25 minutes are too bitty, too diffuse, too full of overfamiliar images of suitcase-carrying refugees being cut down by bullets.
But the show starts to come together when it focuses more tightly on Janina and her parents, and the strains and cracks that begin to appear in their relationships. The piece cleverly takes the watchful, child's-eye view. The internalisation of what is happening lends the crisis even greater emotional depth, a startling intensity - just as when you recall your own childhood, in your mind's eye the colours are unnaturally bright, the sunlight always dappled.
This show keeps on throwing up images that seem frozen in time, like old photographs: desperate people dancing their way to certain death for a piece of bread and jam; Janina dancing her way out of the ghetto; the body of a widower, who discovers that his twin daughters have been taken away, twisting in despair and death on a rope. Most memorable of all is the scene where Janina's mother and father are left behind in the ghetto when she makes her escape, trapped within skeins of yellow wool that form the star of David.
If the first third could be tightened up, this would be a thrilling show. As it is, it cannot fail to move - not least because it doesn't romanticise or turn people into heroes: Janina's parents are portrayed with all their flaws. A Square of Sky shows that survival was a matter of luck much more than will.
· Until Saturday. Box office: 020-8374 0407.
