14-year-old Oliver Cates inadvertently transports Albert Einstein into the present with his computer. Before going back, Einstein helps Oliver work through his anger so he can reconcile with his mother, whom the boy blames for his parents' divorce.

Oliver has no one with whom he can share his secret, so he summons Alexander Graham Bell. However, his secret is uncovered by a curious 14-year-old named Dee Sampson who, thanks to Bell’s advice, Oliver eventually befriends.

Dee is upset by her parents’ investment in a toxic pulp mill, so she summons Joan of Arc to help organize a protest, despite Oliver’s reservations.

Dee’s reticence to leave her childhood behind motivates her to summon writer Lewis Carroll, whose real name is Charles Dodgson, who helps her deal with her grandmother’s death.

Oliver summons Napoleon Bonaparte to help inspire his pals to win a newspaper subscription contest.

Oliver thinks he lacks “the right stuff” where his father is concerned and, at the same time, his friend Bobby is being bullied by the football jocks. With the witty Oscar Wilde as their guide, they both learn that it’s okay to be themselves.

Oliver brings back Beethoven to help Dee deal with a pending operation that could result in her deafness. However, Beethoven is mistakenly brought back from a time when he isn’t deaf yet.

When Oliver plans on revealing his VisiCron technology to the world in return for fame and glory, Dee brings back the co-discoverer of insulin, Dr. Frederick Banting, whose own widespread fame in his day became nothing but an irritant.

Mrs. Tatlow, an impoverished senior citizen, refuses to accept the groceries that Dee has volunteered to deliver over the Christmas holiday. Undaunted, Dee gets a scrooge-like Oliver to call back the real St. Nicholas to help her deliver the goods.

Dee brings in Edgar Allan Poe to help make a Halloween fundraising event spooky, but Poe is charming and anything but scary.

Oliver wants to impress his father by winning a team “orienteering” contest: a race through wilderness terrain with only a compass and a map. For the team supervisor, Dee convinces Oliver to bring back Underground Railroad hero Harriet Tubman.

Dee convinces Oliver to summon Cleopatra to help her audition for a school production of Shakespeare’s Antony and Cleopatra. However, what she secretly wants is Cleo’s advice in winning the affections of school hunk Gino, who is auditioning for the part of Antony.

When Oliver and Anne get lost hiking in the woods, Dee brings back Daniel Boone to help track them down.

Ghostly incidents are happening in the school. To help figure out who is responsible for them Oliver and Dee summon Sir Aurthur Conan Doyle. Oliver keeps questioning this punk looking girl who just seems to appear everywhere. Is she a ghost? Is she responsible for the ghostly incidents?

Dee is running for Student Council but bad rumours about her are going around the school, so she summons Queen Elizabeth I for political advice.

Dee reads Anne Frank's diary entries and decides that Anne deserves 36 hours of free time from the attic hideaway. Anne Frank cannot believe how free it is where Dee and Oliver live from her attic hideaway. Anne starts to really like or should I say love Oliver. Dee and Oliver decide to take Anne to the movie theatre. During the movie Anne steps out of the theatre and meets this punk guy in the theatre's video arcade and finds that there's a lot of goodness in him. So that tought Dee and Oliver how to find goodness in people. At the end of the episode before Anne's 36 hours run out she says that it has been the best 36 hours she has ever had in her life.

Oliver and Dee summon natve American Sacagawea to help in an expedition to expose a refinery that is secretly causing river pollution.

Oliver accidentally causes himself and Dee to be transported back in time by 24 hours, giving them an opportunity to right a wrong.

Dee summons the inventor of basketball, Dr. James Naismith, to coach her on winning an important game.

After Oliver has a row with his dad, Dee brings the man forward in time as a teenager, hoping that they will learn to better relate to each other.

Oliver finds Dee being around this other guy a lot. Oliver decides to bring back Casanova because he thinks that he will be able to give him some tips on attracting girls. Unfortunately Casanova is giving Oliver really bad advice. When Oliver follows Casanova's advice, he makes a huge fool of himself.

When a financial crisis causes Dee's mom to question her faith, Dee brings Moses from the past to advise her, not realizing that she has summoned the young Moses, when he was but a humble shepherd rather than a great leader.

In danger of losing Visicron to a corporate software pirate, Oliver summons the famous 18th Century pirate Black Bart to help him fight fire with fire.

Oliver adds another module to Visicron to speed it up. When Oliver tries to bring back Jack London, the Visicron instead takes Oliver to the time and place Jack London is right now. Oliver has to try and find a way back, so Dee asks Simon to help find a way to bring Oliver back. Meanwhile Oliver keeps altering the future and weird things keep happening in the present.

Plagued by a recurring dream, Dee summons famous prophet Nostradamus to advise her on what it means.

Oliver is just about to delete Visicron before going to college, but then he is transported into the future by an old man. Oliver gets accused by the old man of being careless with time travel. Oliver and the old man watch clips of past episodes on a screen so that Oliver can defend himself and show the man what good Visicron has done. The old man convinces Oliver he shouldn't delete Visicron and then Oliver gets sent back to the present. We later find out that the old man was really Oliver himself as an old man in the future. In the end right before Oliver leaves to Montreal, Quebec, Canada to go to college he gives Visicron to his 12 year old cousin Simon.

Simon brings Oliver back home from the university using the VisiCron to help him with an invention. But there is a glitch in the VisiCron and Oliver is split into two, one nice and the other one is naughty. The nice one cannot tell a lie but the naughty one is seeking revenge on all the people that treated him bad in high school so Crystal and Simon need to find him before he does something really bad.

Simon's hockey team isn't doing that well so he uses the time machine to bring confusious back to the present. At first the hockey team doesn't like him but after he teaches them a few things they are ready to play and win

Simon, Crystal, and Glae try to retrieve the time machine after it's been stolen so they use a device to activate the time machine and bring back Harry Houdini. Glae is getting headaches and starts to disappear, at a fast rate. Thus, Simon must choose between the secrets and confidentiality of the time machine, and saving a friend from not existing.