Here is the summary:

The story tells of a Giant who lives in a castle with a large, beautiful garden filled with soft green grass, beautiful flowers, and peach trees. Every afternoon, the children would come and play in the garden after school. One day, the Giant came back from visiting his friend the Cornish ogre, and saw the children playing in the garden. He was very angry and told the children to leave, saying that his garden was for him alone. He built a high wall around the garden and put up a notice board saying "TRESPASSERS WILL BE PROSECUTED." The children were sad and had nowhere to play. The Spring came, but the garden remained in Winter all year round. The birds did not sing and the trees did not blossom. The only people who were happy were the Snow and the Frost. The Giant was very selfish and did not understand why the Spring was so late in coming. One morning, the Giant heard beautiful music and saw a blossom tree in the garden. He realized his mistake and allowed the children to come back and play in the garden. The garden returned to Spring and became a happy and thriving place once more. The Giant died shortly after being invited to the little child's garden, which was described as Paradise.

I got it from the English subject section of this website.