简介：OneeveningtheCollinsfindtheirmaidMrs.Murdockattheendoftheirsteps:dead,neckbroken.Obviouslyshehadanaccident.Consequentlytheyneedanewbabysitterforanupcomingbigparty.ThesensibleHelenmeetslittleSusanCollinsatthediscountmarketandlikesher,sosheofferstodothejob.Shedoesn'tknowSusan'steenagebrotherMark-technicallyskilledandgoodinschool,butrestiveandcunning.Assoonastheparentshaveleft,hestartspsychologicallyterrorizingHelenandhissisterwithelectronictricks.…