Jo is an Australian girl who lives in the year 1995 who recently moved to New Zealand with her adoptive family. While shopping with her father, Jo enters an antique shop where the owner gives her an antique mirror, insisting that she was meant to have it.
Jo gets a shock when she sees a reflection of another girl, Louisa Iredale, in the mirror. Her family doesn't believe her. Jo returns to the antique shop for answers but the owner pretends he's not there.
Jo and Louisa try to communicate to find out who each are. When Jo touches the mirror her hand goes through the glass, and the two girls can hear one another. After Louisa is taken away for dinner, Jo places her hand through the mirror and it takes her from her room through to Louisa room, which is the same room only 76 years earlier. As soon as Jo is in 1919 a drum of toxic waste appears in the school archaeology well in 1995. Jo discovers Louisa's diary, only to find out it's 1919.