Haven: Return of Sigma tells about a cyborg nammed Sophie and her friends discovering an old journal about the technology of combining two separate animals. The journal also contained information about the Tungaska Event in Siberia. Now, Sophie, her friends and a more then 200 year Lucy Willings must team up in order to stop an evil madman from using the Sigma Technology to take over the world.
- Sophie: Sophie is a cyborg who was saved from near death at the age of 10 by Adam Parks. In order to save her, Adam made a replacement eye, Lung, Arm, Legs and Heart. Sophie now feels isolated with only four good friends and her gaurdian Adam.
- Adam Parks: Adam is Sophies guardian and her late parents closest friend.
- Xander: Xander is one of Sophies closest friends and an expert in technology and History.
- Nick: Nick is a good filmmaker and hopes to make a good movie. Nick is also one of Sophies closest friends
- Chip: Chip is a red haired boy who is good at skateboarding. Chip is also one of Sophies closest friends.
- Vida: Vida is a spunky girl who loves to DJ. Vida is also one of Sophies closest friends.
- Madison: Madison is a introverted and unvarying girl who is very much intereted in motorcycles.
- Lucy Willings: Lucy is a more than 200 year old women. She once worked for Dr. Chanikov on the Sigma Technology. After the Sigma Civil War, she and Rex Chance destroyed the machines and all the Notes involving the sigma technology. When Sophie finds Rex Chances Journal with other notes on the Sigma Technology, she decided to keep it in a High Security Area so noone could get their hands on it again.
- Fredrick Karkaroff: The Main Antagonist. A russian man who plans to use the remaining Sigma Notes to take over the world. He plans to protect the united states by conquering other Communist and Facist countries.