Brooke was born in Chicago, Illinois, the daughter of Mary Lee and Edward Stephen Mendum, and she had a brother named Edward. Brooke began her career in theater and played in the original production of Hair in the roles of "Sheila" and "Jeannie". Additional roles she played onstage include "Linda" in Flower Drum Song and "Rusty", the wife of the late Comedian Lenny Bruce, in Lenny. A December 1972 edition of Gallery said of her performance in Lenny that: "...Mendum displayed a charm throughout the performance that makes another heavy credit for her career most-deserved. [...] We think you will understand our impulse to revive that delightful old custom of flowers in the dressing room and waiting at the backstage door." It was also during her stage career that she worked at the Playboy Club in Chicago, where Brooke became friends with Hugh Hefner.

She made her film debut in 1973 with the hardcore pornographic film Grace's Place, directed by Chuck Vincent. She was also an adult magazine model who posed for such magazines as Playboy and Gallery. Her best-known role was "Anne" in the 1975 S&M drama The Image, directed by Radley Metzger, who reportedly was her boyfriend at the time. In the movie, there are explicit scenes of fellatio and urination; however, Brooke did not perform sexual intercourse on camera. She performed full hardcore sex in the French movie Les Milles et une perversions de Felicia (The Thousand and One Perversions of Felicia), including fellatio and sexual intercourse in 1975. Brooke also appeared in softcore pornographic films directed by Joe Sarno, including Abigail Lesley is Back in Town (1975), Laura's Toys (1975), and Confessions of a Young American Housewife (1974). Brooke also had leading roles (as "Dr. Shirley Jekyll" & "Sherry Hyde") in The Switch or How to Alter Your Ego, The Blazer Girls, and Misty, and she also appeared in Mrs. Barrington and Little Girl... Big Tease. She gave up her film career in 1977.

Although there are rumors that she is still alive and that she may have even faked her death, Brooke died of an accidental drowning due to a fall on July 17, 2012 in Boca Raton, Florida. With respect to her wishes, there were neither announcements nor services of her death.