I expect this explanation to love you, I have made all the one that I have been able so that it is the best summary of all and the thing, most faithful to the movie!!
The film starts with Sakura capturing a new card, the arrow card. The capture with the help of Shaoran, and the Meiling is annoyed because the Sakura keeps the card. At night, Sakura has a strange dream with a chamber with water.
The next day, it is the last day of school before the holidays. The professor divides up the qualifications and to the Sakura they have not gone not at all badly for him, Tomoyo has taken, as of habit, some of the best qualifications of the class, Shaoran has not had bad qualifications either and Meiling takes a great disappointment with hers...
On the way to home Sakura and Tomoyo stop to the store of Maki, Sakura wants to buy a notebook to do the duties of summer. In the store they take part in one of those draws of taking a ball of a box. All her colleagues of class who have taken part, have taken the prizes of consolation, Sakura introduces the hand at the box and the golden ball goes to the hand of Sakura, so she takes the first prize, a journey to Hong Kong.
As her father can not go, Sakura will go to the journey with Touya and Yukito (and with Kero hidden in the bag exchange of Sakura). In the airport they find with Tomoyo, with her cameraman of video and a handful of dresses for whether the occasion rises up. In Hong Kong, Sakura has the same dream with the water and with a mysterious woman as the flame does.
Tomoyo and Sakura keep walking through the street of the birds. This part of Hong Kong has not changed a lot according to Kero. Two strange birds appear and Sakura uses the jump card to follow them. She starts to enter the world of the dreams... but Li arrives and is in charge of arousing her, but she falls to a fountain and she finishes passing for water. Tomoyo is looking for Sakura and it is found with Meiling that she is surprised of seeing her in Hong Kong. Little afterwards Shaoran and Sakura and also Touya and Yukito appear.
Shaoran takes all of them to his house so that Sakura puts on dry clothes. There the 4 sisters of Shaoran that are thrown on Sakura and Tomoyo because it seems them appear that are very monkeys, although the things change when they see to enter Touya and Yukito. The mother of Li who invites them arrives to all of them to stay to pass the night in her house.
At night Sakura has the same dream, this time the woman talks to her and she tells her that she has been waiting for a lot of time. The clothes of the woman start to be moved and she catches Sakura. Sakura is aroused and she realizes in her arms the marks that she has. The mother of Li is going to see that it has happened to Sakura and tells Hong Kong that she has gone for some reason.
The day after they go the home of Shaoran, his mother tells to Sakura that she has to go carefully with the water. Meiling is annoyed because they have to be remained with Sakura, Shaoran Li says that his mother has told him that he takes care of her. In the street they see again to the two strange birds and Sakura and Kero follow them old store up to one where they find a book. In the cover of the book is the woman that Sakura had dreamed of. Sakura enters a sort of trance and tries to open the book.
Kero tries it to stop but is not strong enough. Touya and Yukito enter the store. Sakura opens the book and the store starts to be filled with water. They all remain caught in another dimension. The strange woman appears, is annoyed because she had made come to Clow Reed. Shaoran arrives to help Sakura and fights while she tries to save those ones. She only obtains to rescue to Tomoyo, the rest remains caught in the other dimension.
In the store, Sakura, Tomoyo and Kero, look for the book to be able to help those ones. Kero remembers who is this woman, is a competitor of the Clow Reed that using her magic did a spell so that the spirit was not been without taking revenge on Clow Reed catching him in the other dimension forever. There has to be a connection among ours dimension and the other one, and Sakura remembers the fountain in which she fell the previous day that she is the same one that there was in the cover of the book, so this has to be the door among the dimensions. Tomoyo, Kero and Sakura go to the fountain, but a too powerful barrier is created for her. The mother of Shaoran arrives and with her magic opens the barrier, enough so that she can pass Sakura and Kero.
There she finds again the woman, and asks him because she has returned and also asks where she is Clow Reed. Sakura realizes that she is fallen in love with Clow Reed. She starts to fight, Sakura uses the arrow card to attack:
-Sakura: "Really esteem, truth? Is, truth, very hard? losing somebody to who owners, very hard, truth?"
-Maga: "Is it true that Clow Red is dead? I have waited so much time for it... there was something that wanted him to say it"
The woman starts to evaporate. They all remain free after that and return with Sakura. At the end of the film Sakura says that on the contrary that this woman, she some day will tell her real feelings to the person that she loves.