It is the story and adventures of Margo, a little mouse who lives in a large tree made chalet. Small Margo has as neighbors Eliana, a squirrel who lives on the top floor; and Dennis, a dormouse that lives in the basement.

However, all is not happiness for Margo. The little mouse must deal with some enemies. One day, Eliana goes to visit her mother because she is sick and Margo must look after the house. Then, at night, a sullen owl settles in Eliana's house illegally. So Margo seek ways to take the owl out of the house of her friend. On another occasion, Margo prevents a beggar rat from occupying her home without her permission. Like while hiking should avoid being eaten by a stork. Although Margo has good friends like Anna, a sparrow; or Christophe, a cricket who likes to play the violin. With her friends, Margo lives many adventures.