the unfortunate policeman took several good blows to the head before he was swapped for a filing cabinet , which pagan next balanced on a chair , castors sizzling like castanets , his dance along the corridor accompanied by gunfire in short , deliberate snatches , his exit via the sixth floor window an elegant surfing of air and glass that culminated in a finale of trashed prowler roof-light clusters and a curtaining snowstorm , h through m of known paedophiles to disguise , genielike , his exit .