Following on from Cathy's Book and Cathy's Key, 18-year-old Cathy wakes up one morning to discover three dead bodies slumped outside her house in San Francisco. One of the Eight Immortals, Ancestor Lu, is sending hired assassins after Cathy because she stole the mortality serum (this has the power to render even an immortal mortal). Cathy runs away from home to be pursued across the state, accompanied by broken-armed Denny, ingenious best friend Emma and techno-savvy Pete. Will Cathy escape Ancestor Lu's clutches? And can she keep 'evil twin' Jewel and boyfriend Victor safe?