Replacing the old Mad Hatter as head of the Mad Tea Party, she is the leader of the Land of the Looking-Glass. She's the second most powerful figure in all of Wonderful, competing against the Queen of Hearts for total control. She develop a grudge against Alice Stetson when she promised the Queen Queens, New York as her new kingdom. So the Mad Hatter and the March Hare ascended into Alice's world and abducted her daughter, Chloe. This forces Alice to go into the Land of the Looking-Glass with the Caterpillar, the Cheshire Cat, Jack the White Knight and the White Rabbit.
The Hatter had already caught the Caterpillar, the Cat, and Jack. Alice had a plan to get the Rabbit caught, and use his power to turn back time with his watch to return the people back to their old selves before the Land of the Looking-Glass affected them. In the meantime, she was talking to the Queen of Hearts, telling her that Alice and her friends were traitors, planning to betray her, and asks her to be present at their beheading. Unknown to the Queen, the Hatter plans on executing her last.
When the Hatter arrived, she found that her prisoners escaped and taunted Alice with one final riddle, Alice learns that the Hatter is the alter-ego of herself. Alice did not come to Wonderland when she was supposed, due to her mother's death and her childhood coming to an end, over two decades prior. Due to this, the Hatter was created out of every bad moment Alice has ever faced in her life. When the Queen arrived, Alice present her with the execution orders the March Hare gave her, with her name on it. The Queen, learning of the Hatter's plan to behead her, wanted to banish the Hatter to the underground world beneath Wonderland. Alice, who tries to defend the Hatter, saying the Hatter doesn't have to be alone. The Hatter said she would like that, and asks her to take her hand. But then she pulled Alice to her and held her at knife-point. Then the Caterpillar and Cheshire Cat show up, detracting the Hatter, giving Jack the chance to save Alice and hold the Hatter at bay. Jack sacrificed himslef so the Queen can banish the Hatter, sending them both down to the underworld.