NEW YORK - As Marcia Brady on "The Brady Bunch," Maureen McCormick projected an image of the wholesome girl next door. But off camera, she spiraled downward into drug addiction and depression.

Now 52, McCormick writes about her struggles in a new memoir, "Here's the Story: Surviving Marcia Brady and Finding My True Voice," hitting stores Tuesday. She discusses her romance with TV sibling Barry Williams, her dates with Michael Jackson and Steve Martin, cocaine binges and parties at the Playboy Mansion and the home of Sammy Davis Jr., an unwanted pregnancy and trading sex for drugs.

McCormick was 14 when "The Brady Bunch" debuted on ABC, running from 1969 to 1974. Despite her role as a sunny Miss Perfect, she struggled privately with anxiety and insecurity, the youngest of four children born to a mercurial father who abused and cheated on their mother.

"As a teenager, I had no idea that few people are everything they present to the outside world," she writes in the book, published by William Morrow. "Yet there I was, hiding the reality of my life behind the unreal perfection of Marcia Brady. … No one suspected the fear that gnawed at me even as I lent my voice to the chorus of Bradys singing, `It's a Sunshine Day.'"

When "The Brady Bunch" ended, she took up a hard-partying lifestyle in Hollywood, using drugs including cocaine and Quaaludes. She struggled to regain her earlier success, landing some TV and movie roles, but developed a reputation for unreliability due to her addiction, even botching an interview with Steven Spielberg because she was high.

After interventions, stints in rehab and experimental therapies, McCormick began getting sober in 1985 when she married actor Michael Cummings, with whom she has a daughter, Natalie. She continued to fight depression through therapy, medication and the help of "Brady" cast mates.

McCormick, who is also a singer, starred on the Country Music Television reality series "Gone Country" and "Outsider's Inn." She also confronted her weight issues several years ago as the winning contestant on the VH1 reality show "Celebrity Fit Club."

As for her iconic role, "I'll always be struck by how much a part of people's lives Marcia is and always will be. But now I'm not bothered by the connection. It took most of my life, countless mistakes and decades of pain and suffering to reach this point of equanimity and acceptance," she says.