Berta is a six-year-old girl who lives with her mother and her little brother, a one-and-a-half-year-old boy who can’t yet walk or talk and whom she always calls Snot.

On the first day of school, Berta discovers Pipo, an alien who fell from the sky, in the backyard. Berta decides to take him to her room, unaware that Pipo is very different from her: noisy, messy… and with a voracious appetite that leads him to eat practically anything. But besides being very hungry, Pipo is hiding other secrets.