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.

After returning back to 1995, Jo is in a good mood, thinking that she had changed history and that Mia and Jessie were no longer sick. A surprised Tama and Royce, who had thought that she would never get back from 1919, tell her that Mia and Jessie are still in hospital. When Jo hears what Jade has been saying she is more than a little upset. Jo's parents of course don't believe anything that she has to say. In the evening back in 1919, Louisa's father asks her to tell him everything that she knows about the toxic drums, and that when Jo returns, he wants to talk to her. Sir Ivor convinces Nicholas to give him his family signet ring for safekeeping. Nicholas asks Louisa to help him find about what happened to his family.

Despite what Tama and Royce thought about her not going back, Jo does anyway. Using his computer at home, Tama finds a site which has formula's to neutralise the toxic waste. Meanwhile, Catherine has decided that she has had enough and tells the rest of the family that she is going to resign as school principal. While doing some more research, Tama finds a report about toxic substance which mentions Sir Ivor from 1919. Nicholas has been locked in his room, and wants Jo and Louisa to help get him out. Sir Ivor refuses to give back the signet ring to Nicholas.

By pretending to collect Sir Ivor's dirty washing, Jo is able to sneak into the house. She finds Nicholas, who refuses to leave without his ring. Later in the night, Louisa, Jo and Nicholas 'borrow' a hansom cab and follow Joshua, Louisa's father, down to the wharve where his is further investigating the toxic substance. Just after Joshua finds the waste, he is attacked by Sir Ivor's men, and he is effected somehow by breathing in the toxic substance. Jo and the others find Joshua and return him home, before leaving the warehouse though, Jo picks up the drum that is still there. Jo is about to prove to Primrose about the toxic drum, but when she goes outside to get it, the hansom cab and the drum are gone. Back in 1995, and after a pep talk from Royce, Catherine decides not to resign.

As far as the Iredale's know, Joshua is dying from the effects of the toxic substance. Seeking help for Jo, Old Nicholas, the man who owned the shop, tells Royce that he has to go through the mirror. In the next yard, Sir Ivor hears Royce shouting his warning to Jo, who already knows what he had to say, but it creates a distraction to allow Nicholas to sneak back into the house. Louisa goes through into 1995, and Tama and her go to the library to see if they can find out whether or not her father survives. He does survive, but they discover that he dies in a train crash in 1928 because he didn't want to fly by aeroplane. Just as Louisa is about to go back through the mirror, Andrew walks in and demands to know what is going on.

While Andrew is getting the drift of what's going on from Louisa and Royce, he is convinced only when he sees Louisa go through. When he tries, it won't let him follow. He tells Catherine, and they attempt to show her, only the mirror has been moved in 1919. Jo continues to look for the missing drum, followed by a less than discret Frid. Frid then approaches Sir Ivor and informs him that it is he that now is in possesion of the drum, and that Nicholas was involved in helping save Joshua. Meanwhile, back in 1995 Old Nicholas gives Jade some new instructions, which she has to follow exactly.

After falling from the water tank stand, Nicholas injures his arm. Not being able to find the girls in the house, he goes into the school room. While in there he finds Jo's encyclopedia which tells of what really happened to his family. It is at this point we find out that he was the son of Tsar Nicholas II, Alexi Romanov. Jade is again given instructions and Old Nicholas says that if she follows them exactly, she'll never see Jo again.

The pieces of the story start making sense when Nicholas tells Jo and Louisa how he came to be in Sir Ivor's care. When Frid returns back to the house they hide Nicholas, Nicholas however still wants to know where the encyclopedia came from. Jo convinces him then of her story when she shows him the mirror. Back in 1995 Jo wants to get the cure for Nicholas, only Nicholas needs to actually be there. Meanwhile, Primrose has discovered Nicholas in Louisa's room and after a doctor looks at his arm he gets escorted back to Sir Ivor's. In order to keep up contact with Nicholas, Jo sends a walkie-talkie over to him in some books.

Nicholas has to watch in horror as his ring is dropped into the toxic waste by Sir Ivor. Sir Ivor is also busy planning the arrangements, with help from Salisbury, to get the drum out by train. Meanwhile a foolish Titus gives Sir Ivor the mirror in exchange for a cricket bat, the mirror getting locked in the cellar. In 1995 Jade is told by Old Nicholas to take Jo's mirror to the school cellar where she then witnesses Jo coming through it, without the drum.

With the help of Ani, Louisa is able to follow Sir Ivor and Campbell to the train station. The girls hoping to be able to make the split second alignment they need. At the other end Tama is waiting to catch the train in 1919 with Jo and the train is running late. The alignment works and Jo is sent through to 1919 to a very surprised Louisa, but Sir Ivor is aware they are there thanks to Campbell. The drum goes overboard and the girls jump off the train. Campbell pursues but is unable to catch either of them.

Tama is in trouble with Jo's dad and he warns him not to help Jo to go back through once she comes back. Catherine is having trouble of her own after being sacked as headmistress, not wanting to stay she decides that the family is moving now. Bakc in 1919 things are looking up as Mr Iredale has recovered. Things aren't looking so good for Titus when the girls discover he is to blame for the mirror getting into Sir Ivor's hands. Mr Iredale sends a team of soldiers to look for the missing drum, which turns out to actually be the drum of cooking oil. When Jo tries to get to see Nicholas to tell him that they weren't able to get his ring, she is caught and taken to the local jail. If her parents don't claim her in two days she will be sent to a women's prison in the South Island.

After her father refuses to help get Jo out of jail, Louisa returns back to 1995 to ask Tama for her. Royce at that moment is getting a well deserved revenge on Jade, which leaves her less than impressed. The remote control toys that Royce used however, give Tama an idea of how they can rescue Jo, together they all make the plan. Royce was going to go, but at the last minute his mother insists that he helps to start packing. So Tama tries again with the mirror and this time goes through. Louisa tells Titus to guard the mirror, which prevents Frid from stealing for Sir Ivor. By the end Jo is out of prison and she and Nicholas leave on horseback to go into hiding.

Primrose believes Louisa's story of Jo, and gathers together food and blankets to take to them while they are hidden in a unused summerhouse. Frid overhears and follows them to where Jo and Nicholas are hiding and reports back to Sir Ivor. Sir Ivor re-captures Nicholas and informs him that he is sending him back to Russia. Back in 1995, the mirror has been packed away, being on a deadline Tama and Andrew open up all the boxes to find the mirror and then get it to the graveyard just in time for Jo to escape being caught back in 1919.

Scared that she will become trapped forever in 1919 Jo admits her fears. Sir Ivor is less than impressed with Frid for losing Jo and Primrose must answer to Sir Salibury concerning Jo's escape. Nicholas manages to get a note to Louisa and Frid is sacked from service in the Iredale household. Meanwhile, Titus is busy following Frid to find where the drum is kept.

After copying the formulas of the two agent down, Tama begins work on making them. Jade again surprises Jo, who gives her the key to Nicholas' room which allows her to once agin rescue him. Louisa, Jo and Nicholas swap the drum of cooking oil for the toxic waste. Campbell chases them and threatens to open the drum with the poision. Meanwhile the Russians have come to collect Nicholas and take him back. Sir Ivor makes excuses and asks them to be patient and to come and enjoy the ball.

After Nicholas hides the drum down the well, he and Jo argue, after all it was what she was trying to prevent in the first place. Sir Ivor is trying to keep the Russian men happy before the ball as they wait for Nicholas to be handed over to them. Out in the garden, Nicholas teaches Jo how to dance the old fashioned way, they kiss and realise that if it workd they may not be together. Tama arrives in 1919 which the remainding two agents, one of which Nicholas must chose, as they only get one shot at it. Meanwhile in 1995, Catherine and Andrew go to the shop and visit Old Nicholas, Catherine guesses his true identity.

Catherine and Andrew are at the shop with Old Nicholas, who informs them of what will happen once Nicholas has choosen the correct agent. At the ball, Frid decides to get Sir Ivor back, only to make an idiot of himself by producing the drum of cooking oil. Sir Salisbury, Sir Ivor and Frid are all arrested. When Jade goes through the mirror and tells Nicholas to chose the other one, he decides on the agent and mixes into the drum. Back in 1995, Jo and Tama collect the ring and go back to Jo's house where Louisa and Nicholas are waiting. Nicholas finds however that he can't go back to 1919 with the ring. He makes the decision to stay and the mirror vanishes just after Louisa returns home.