Mew, a stubborn kid, is neighbor to Tong, an energetic boy who lives with his parents and sister. After accidentally spitting gum into Mew’s hair, Tong wanted to befriend Mew but was unsuccessful. At school, Mew was cornered by several other students was harassed until Tong stepped in to defend him. Tong was injured and apoligized to Mew for the chewing gum incident. Mew was grateful for Tong stepping in and responded that they were even. The two became good friends from that point on.

Mew plays on his grandpa’s piano and is joined by his grandma, who begins to play a song. Mew asks his grandma why she liked that song and his grandma responded with telling Mew that it was played for her by his grandpa. It was a way for him to express his love to her and explains that one day, Mew will be able to do the same for the person he loved.

Tong’s family goes to Chiangmai and returns without Tong’s sister Tang since she wanted to stay with her friends a couple days more. Tong bought Mew a present and decided to give it to Mew piece by piece in a game of Treasure Hunt. One by one, Mew found all of the pieces except for the last one which was hidden in a tree. The tree was cut down before Mew was able to retrieve it leaving the present Tong bought for Mew incomplete. Tong was disappointed at their misfortune, but Mew remained grateful for Tong’s efforts. Tang called her parent’s and told them that she would extend her stay at Chiangmai until the 24th of December. Tong looks at his calendar and realizes that Tang will not be able to attend the Christmas play he would participate in.

After the Christmas play, Tong receives a phone call from his parents telling him to stay with Mew and his grandma. After spending the night at Mew’s house, Tong awakens to the sight of his parents along with Mew and his grandma. Tong is told that his parents are going to Chiangmai a couple days to look for Tang. Tong lives in depression until his parents come back, only to find out that Tang may be lost. Tong is devastated and cries in front of Mew, who is trying to comfort his friend.

Months have passed and Tong’s family decides to move. On the day of the move, Tong finds Mew sitting on a ledge overlooking a pier. Tong says his final words and departs in a car. Tong looks back only to find Mew walking towards the car before coming to a stop and crying for losing his best friend.

The boys are reunited during their senior year of high school at Siam Square. The musically talented Mew is the leader of a boy band called  August. Tong has a pretty girlfriend, Donut. The meeting stirs up old feelings that Mew has harbored since boyhood, his love for Tong.

Mew’s band, meanwhile, has a new manager, June. She looks just like Tong’s long-lost sister, Tang. After meeting June, Tong and his mother, Sunee, devise to a plan to pay June to pretend she is Tang, in hopes that it will pull Tong’s father out of his alcoholic depression. Tang borrows a story from the Thai film Ruk Jung, saying she has amnesia, which is why she has forgotten how to say her family’s Catholic grace at the dinner table.

Mew is also the object of an unrequited crush of a neighbor girl, Ying. But Mew has strong feelings for Tong, which have inspired him to write new songs.

The manager as well as the entire band were all impressed with Mew’s composition.

The boys share a prolonged kiss in Tong’s backyard one night after a party in honor of the return of Tang. 

Tong also spends the night with Mew, which causes his mother to worry.

At Christmas time, as Tong and his mother are decorating a Christmas tree, they have a heart-to-heart talk about making choices, and Tong asks his mother to let him make his own choices.