Della has just begun at a new school and is missing her friends. The girls at the village school are all part of a gang led by Amy, who is an arch manipulator. Things deteriorate badly when the gang, ostensibly being friendly, lock Della up in a deserted cottage. During her hours there, Della meets the ghostly inhabitant of the cottage, Emerelda - an old lady. As the bullying at school gets worse, Della develops her friendship with Emerelda (who doesn't believe in humans and is very dismissive of Della) and also meets George, another ghost, and Ada, ghostly forbear of Amy and quite as nasty. Della comes to depend on the ghosts' friendship, and when they finally announce regretfully that they must leave because their two worlds must remain separate, she is distraught. There is an ensueing accident. Della falls into the river, whether deliberately or not even she is not sure, and her parents and the school are finally made aware of the severity of the problem. One of the gang, who has shown signs of trying to be friendly, helps Della adjust, and the girls (except Amy) admit their guilt. The ghosts may or may not have been in Della's imagination, but their local contacts seem to make them real enough. Whatever the truth (and this is purposely left a bit vague), the seriousness of Della's feelings about the bullies is made crystal clear. This is a serious novel with undertones of humour that make the story more palatable.