Early20thcentury.Polinaarrivesatagirls'boardingschoolonamysteriousislandtofindhersisterwhodisappearedunderstrangecircumstances.Polina'sinvestigationiscomplicatednotonlybyconflictswithothergirlsandtheimperiousmentorZakharovabutalsobyastrangeobsessionthatdrivesthegirlsmad,oneafteranother.Polinaneedstofindoutwhathappenedtohersisterwithoutlosinghermindintheprocessandgetofftheislandwhichissinkingintheabyssofinsanity.