In "The Girl Who Drank the Moon" by Kelly Barnhill, some important events that take place in the first four chapters include:
The annual ritual of leaving a baby as a sacrifice to the witch who lives in the forest. This ritual is carried out by the people of the Protectorate, who believe that the witch, known as the "Monster," is the only thing keeping them safe from harm.
The witch, known as Xan, who instead of hurting the baby, she adopts and raise it as her own. She discovers that the baby has a powerful magical gift, and decides to protect her and raise her with care.
The arrival of Luna, the baby who is left as a sacrifice and is saved by Xan, to the Protectorate and the beginning of her journey to understand her powers and the truth about her origins.
The introduction of Antain, a boy from the Protectorate who is desperate to leave his home and travels to the witch's forest to find Luna, who he has grown to love.
These events set the stage for the story and introduce the main characters and the conflict that will drive the plot of the novel.