Le pire anniversaire de ma vie (Hélium)

The small group of passionate readers of the treehouse, hidden among the trees, is growing. They meet Oscar, a boy who lives at the end of the path. He is an expert on birds and it is he who takes on the role of the reader of a book about birds.

Tiago and his friends play a guessing game and accuse him of cheating. He decides to stop playing and teases Fanny by saying she can't read and asks her to read to prove she can. So she reads the story of Gaston who has an imaginary friend, a little bird.

Tiago wants to play the pirate game while his friends want to read a book. He pretends to fall down and that his eye hurts. His friends end up pretending to play doctor so they can check what's really going on with him. They end up concluding that Tiago's misadventure is the same as the story of Emile who wanted a cast. …

Esteban is training Antoine so that he can have muscles to have more friends in his new classroom. Lisette reminds him that having muscles is not necessarily the best way to make friends. They read the story of the penguin who was cold. Antoine realizes that he has very good friends in the treehouse and that he will end up making good…

Fanny and Tiago share their vacation stories. Lisette is sad and refuses to play with them. To help her, Fanny reads a story to find out where her sadness comes from.

Lisette and Oscar contemplate the stars in the sky and Fanny is too small to see them. Suddenly, they see a shooting star and realize that Fanny couldn't see it. She thinks she's too small and that the grown-ups don't want to involve her. To reassure her, Lisette reads her the story of the little bird that swallowed a…

Lisette rehearses for her show and asks Tiago to help her practice by reading with him. He gets angry and refuses to read, insisting that he hates reading. She suggests to read Albert's story that reminds him of Tiago.

Tiago is sad because his rabbit died and his parents want to adopt a cat instead. He refuses to replace his favorite companion. Lisette suggests reading the story of Poppy and Chouchou to cheer him up.

Tiago brings the drawing of his portrait and his friends think he drew it. He doesn't have the courage to tell the truth. Lisette who notices his lie suggests reading a story to encourage him to tell the truth.

Tiago and his friends have fun measuring different parts of their bodies and think that the greater the dimensions, the better they are. They end up asking Antoine to decide who is the best. After some reading, they quickly realize that you can certainly measure some things but not feelings.

Tiago builds castles of cards, but he becomes furious when they quickly fall apart. Lisette thinks that his anger is similar to the one of a little red prince in one of his books.

Friends are fighting with pillows and chasing each other around the treehouse. Fanny becomes a little sad when she learns that they are playing a war game. It reminded her of one of her books. She sits down and reads the story of two friends who are forced to separate because of the war.

Fanny and her friend think they are alone in the treehouse and start performing ballet. Esteban arrives and decides to leave because he thinks that classical dance is just for girls. Fanny tries to convince him to stay and read the tale of a prince and a princess.

Tiago catches Basil making a flower wreath for Lila. Tiago thinks it's better when you give a brand new gift like his glasses. Basile doesn't have the courage to give his surprise anymore.