Jo Tiegan is an adopted 14 year old living with her mother Catherine (Judy Mcintosh), a school principal; father Andrew, an aspiring writer; and her younger brother Royce. While shopping with her father, Jo enters an antique shop where the owner, an eldery gentleman gives her an antique mirror, insisting that she was ment to have it. Later on that day Jo gets shocked when she sees a reflection of another girl, Louisa Iredale in the mirror and realizes that the mirror is a travel device to the past. While trying out the mirror, a drum of toxic ends up in the school archeology well. Next day, Jo's best friends, Mia and Jesse get splashed by the same toxic drum and end up in hospital.

Louisa travels to 1995 and comforts Jo, who blames herself for the sickness of her friends. She gets an idea to travel to 1919 and stop the toxic drum from getting into the well. Tama Williams, Jo's best friend does not believes her until she shows him that she can travell through time, but he is unable to go after her. While trying to go through Tama moves the mirror from it's alignment and breaks the position. Titus Iredale, Louisa's little brother, is convinced that Jo is a ghost until Jo and Louisa prove him wrong and make up that they are searching for buried treasure, just to get him to help them look inside the neighbour's well. The owner, Sir Ivor Creevy-Throne, catches them in their search. Later on, Sir Ivor's ward, Nicholas, who watched the incident in the yard. He wants to meet the world outside his bedroom.

When Jo discovers that she can't go back through the mirror to 1995, Louisa's mother, Primrose finds the two girls in the bedroom. Like everyone else, she doesn't believe what Jo has to say. Louisa's father agrees to let Jo stay at their house, after tehy convince him that Jo is lost. Later on, the girls once again sneek over the fence into Sir Ivor's yard to try and find the drum, all the time being watched by Nicholas. Nicholas insists that Sir Ivor allow the girls, and Titus over for afternoon tea. Catherine meanwhile is dealing with Jade's mother, Dr Coigley, who asks Catherine to resign as principal. Meanwhile, Tama is trying to convince Royce that Jo went through the mirror. After stealing the keys, and borrowing Dr Coigley's they get into the lab to do some 'tests'.

While going to the 'toilet' Jo is caught by Sir Ivor in his cellar. She again tries to tell him about the drum of toxic poison, but he dismisses it as a wild imagination. But like any gentleman would, he agrees to have the well boarded up as it is used. By the time they return, Titus has convinced Nicholas of what a great game cricket is, Sir Ivor agrees to let Nicholas go, as long as the Iredale's tutor, Frid, goes with them. Sir Salisbury visits Joshua, Lousia's father, to put an end to rumours that had been going around about toxic waste. Back in 1995, Jade brings a 'present' for Jo and insists on leaving it in Jo's room. Instead she decides to take off with the mirror. On the way however, the old man from the shop stops her and tells her to return the mirror immediately. Tama and Royce by this time are wondering what Jade actually knows. Back in 1919, Titus, Jo and Louisa are playing cricket in their backyard, only for Jo to hit the ball and send it flying through Lousia's window.