Like Cassie Blake, Kori was born outside of Birthday Season on September 22, 1977 to Carmen Henderson and an unnamed father. She was the younger sister of the Henderson brothers, but unlike her brothers, Kori's birth wasn't planned by Black John. She presumably grew up on Crowhaven Road like the rest of the Circle, with complete knowledge of her witch ancestry.
As Kori's fifteenth birthday was approaching, she would eventually be initiated into the Circle and become a true member. However, after Cassie Blake moves to town, Kori is found dead with her neck broken. This incites anger within the Circle, especially the Henderson brothers, who believe that it was human Outsiders who have murdered Kori. 
It is eventually revealed that Sean Dulany killed Kori to make place for Cassie in the Circle. Unbeknownst to everyone at the time, Sean wore a piece of hematite that made him vulnerable to Black John's influence. Because Kori was not included in Black John's plans, he made Sean lure her out to New Salem High School one morning and push her down a flight of stairs, killing her. 
- Kori's death mirrors Amelia Blake's death from the TV series in the sense that they were both murdered to get Cassie Blake to complete the Circle.
- Like Jeffrey Lovejoy and the principal, Kori was killed in a manner similar to the way the puritans used to execute people accused of being witches.