Tully Hart is a fictional character from the novel "Firefly Lane" by Kristin Hannah. She is portrayed as a vibrant and ambitious woman who dreams of becoming a successful television producer. Tully's personality is marked by her strong will and determination, often leading her to take risks in both her personal and professional life. Throughout the story, Tully's complex relationship with her best friend, Kate Mularkey, is a central theme. Their friendship faces various challenges, including misunderstandings and life changes, but ultimately highlights the importance of loyalty and support in enduring relationships.