Kelsey gets bored and walks out of the tour to phone her friend , but disturbs the Bane Mother . Mrs Wormwood tells her staff not to ring any sirens and to kill Sarah Jane Smith . Kelsey wanders from the tour and attempts to phone her friend , but disturbs an unknown beast , the Bane Mother , to the annoyance of the staff , to which Wormwood orders the alarms switched off and Sarah Jane killed .