The Thea Sisters have gone on many adventures since Thea taught them their journalism course. Traveling all over the world; they have gone to Australia, Japan, China, France, Spain, Hawaii, New York, Alaska, England, Peru, USA, Canada, Egypt, Italy, Turkey, India, Scotland, Germany, Iceland, Madagascar, Brazil, Greece, Russia, The Netherlands, Africa, Malaysia, and The Bahamas.They have also traveled to space! Usually their adventures lead them on missions and quests, which is/are sometimes not expected. They always find the culprit in the end.They always make new friends on their adventures.
- Nicky - She is a mouselet who loves being outdoors. Nicky is claustrophobic - she can't stand small places. She is also always in a good mood when she's outdoors. She is from Australia.
- Colette - She is particular about her appearance. Colette is also energetic and full of great ideas. But despite that, a weakness of hers is that she's always late, according to the Thea Stilton books. She is from France.
- Violet - She is a shy mouselet who wants to be a violinist. She is a real intellectual, and she is detail-oriented and always open to new things. According to the Thea Stilton books, Violet is a bit sensitive and can't stand being teased, and she can be a real grouch if she doesn't get enough sleep. She is from China.
- Paulina - She is the computer genius of the group. She loves to help other rodents, and loves traveling and meeting people from all over the world. She is also very close to her sister, Maria. She is from Peru.
- Pamela - She is the pacifist of the group. She loves to eat pizza, even for breakfast! Pamela is also a peacemaker. According to the Thea Stilton books, a weakness of hers is that she is very impulsive and that any mechanical problem can be solved if she is given a screwdriver. She's from Tanzania.