InsomniatellsthestoryofsuccessfulcareerwomanEmmaAverill, whofearssheislosinghermindaftersufferingfromsleepdeprivationtwoweeksbeforeturning40.Hermotherhadasimilarexperienceatthesameage, sufferingaviolentpsychoticbreakdownonthenightofher40thbirthday.Butevenassherelivestheexperienceofhermother, Averillbelievesotherforcesmaybeatwork.Hermotherishospitalizedwithasuddeninjury, herestrangedsisterreturnswithoutwarning, andshefeelsasifsheisbeingwatched.Onlybyinvestigatingthetruthofherpainfulpast, canshefindtheanswerstoherpresent.