The series begins when Catherine Chandler becomes a victim of mistaken identity and is viciously attacked and left for dead in Central Park. A shadowy figure named Vincent rescues her and takes her to a mysterious Tunnel World that exists below the city streets of New York City to recuperate. During this time, Catherine develops a strong bond with Vincent and later she discovers that Vincent is half man/half beast. Later, Catherine's new job with the District Attorney puts her life in peril and somehow Vincent is able to sense when she is in danger.