Tracy Carstairs never appears on the screen. She is the only niece of the Carstairs family in "Black Magic".
In 1958, Tracy runs away from the Carstairs family to join the circus. She has not been seen by the Carstairs since then.
In 1976, Old Cyrus Carstairs has developed a high-speed alloy to be used in jet fighters. He is about to sell the formula to the OSI for 20 million dollars before he dies. Foreign powers are offering millions to purchase the formula. With the approval of Tracy, Jaime Sommers is sent to the Carstaris' estate impersonating Tracy to obtain the formula.