Filch and Umbridge were standing, apparently transfixed in horror, halfway down the stairs. As Hermione watched, one of the larger Catherine wheels seemed to decide that what it needed was more room to manoeuvre; it whirled towards Umbridge and Filch with a sinister "wheeeeeeeeee'. They both yelled with fright and ducked, and it soared straight out of the window behind them and off across the grounds. Meanwhile, several of the dragons and a large purple bat that was smoking ominously took advantage of the open door at the end of the corridor to escape towards the second floor.