It is an early spring evening in 1943 when the air-raid sirens wail out over the East End of London. From every corner of Bethnal Green, people emerge and set off for the shelter of the tube station. But at the entrance something goes badly wrong, the crowd panics, and 173 people are crushed to death. When an enquiry is called for, it falls to the local magistrate, Laurence Dunne, to find out what happened during those fatally confused minutes. The more questions Dunne asks, the more difficult it becomes to disentangle truth from rumour. It is only decades later, when the case is re-opened by one of the children who survived, that the facts can finally be brought to light.