In the movie, a woman named Alice goes to (what will be) her engagement party. When the man proposes to her there, she cannot decide, and when she sees a rabbit in a coat, she flees from the party and follows it. It leads her to a hole, which she falls into. She enters wonderland, and meets an assortment of creatures and people. The creatures believe she is "The Alice" who had been to wonderland before, but she does not think so, because she does not remember it. They tell her that she must defeat the evil Jabberwocky in order to rid wonderland of the tyranny of the Red Queen.
I will not go on, so that I don't give any spoilers, but that is basically the plot.