Leffler, a talented actress, made a significant impact in the fourth season of The 4400, taking on the complex and intriguing role of Cassie Dunleavy. Cassie's character possessed a unique psychic ability, serving as a guide for Kyle Baldwin as he embarked on a transformative journey to become the shaman that helped Jordan Collier lead the 4400 to establishing a utopian colony in Seattle by the end of the season.
Throughout her appearances, Cassie played a crucial role in helping Kyle locate a mysterious book of prophecy from a 1918 cult, which contained a vivid drawing of Collier and a list of individuals who would need to take the promicin shot to bring about the next stage in human evolution. Her guidance was instrumental in Kyle's quest, allowing him to uncover the secrets of the 4400 movement.
Moreover, Cassie demonstrated her empathetic nature by helping Kyle bring his cousin Shawn out of a coma with an injection of promicin. This selfless act showcased her compassionate side, highlighting the depth of her character and the impact she had on those around her.
