"And I'm supposed to lead this team!"
Madelaine "Maddy" Carter is the leader of the Timeriders team. She is a support unit developed by Roald Waldstein to resemble his late wife. She falsely believed that she was saved from a terrorist attack on a plane by Foster so that she could become a TimeRider.
Maddy was made to believe she was a computer hacker for Microsoft.. She was supposedly aboard an aeroplane in 2010. Leaving the toilet cubicle she was addressed by an old man behind her, asking her if she was Madelaine Carter. He told her that the plane they were on would explode and crash in a matter of minutes because of a bomb placed on board by terrorists. At first she thought he was a terrorist himself but he quickly convinced her he was from the future by telling her all sorts of information about her, and claimed that she could save her. She panicked and took his hand and everything went black along with a falling sensation.
In reality, Maddy was created by Waldstein and was released into the TimeRiders' base when she had grown to about the age of 18.
She arrives in the bunker confused, like the others. Foster tells her she is important to the team because of her computer skills. Foster tells her she will have to be leader soon because he is dying. He tells her more about time travel than the others, like how Liam is going to age very rapidly from all the time travel he will do. During the Apocalyptic New York, she, Foster, and Sal try to get Liam and Bob back from World War II, and have to find a power source. When the team goes looking for diesel, Sal gets taken by the cannibal-gollum remains of the human race and Maddy wants to save her. Even though she wants to, she knows that if she goes after Sal, she would get killed, too, so she goes back to the bunker. There, as she is waiting for the generator to start working, the bunker gets attacked by the "humans." She just manages to bring Liam back and then send him back to fix history. Liam succeeds and comes back. Later, in a Starbucks, Foster tells Maddy he is leaving and she is now in charge. She doesn't think she is ready but accepts.
Maddy was the first to find out about "Pandora". She recieved a scribbled note at the 1906 drop-point. In The Eternal War we find out this was left by Joseph Olivera. Co-creator of the agency. Pandora is the Holy Grail. Becks is the only member of the team that knows the secret of the Holy Grail message and can only tell the team (Maddy specifically) when it is 'The End'.