In the 1970s, Tatum O'Neal was known as "Ryan's Daughter." By the '80s, she was the battling bride of tennis star John McEnroe. But throughout the '90s she kept a low profile. This week, she emerges on the cover of PEOPLE, and her tale, as the magazine notes, makes the most shocking "E! True Hollywood Story" look like "Sesame Street." Abandoned by an overwhelmed, drug-abusing mother (actress Joanna Moore) at age 7, Tatum was an Oscar winner at 10 (for 1973's "Paper Moon," costarring her father, Ryan O'Neal) and began using drugs by 14 -- moving eventually from marijuana, Quaaludes and cocaine to heroin. With her father caught up in the celebrity scene of the 1970s, a teenage Tatum and her younger brother, Griffin, were left on their own in Ryan's Malibu house while their father moved in with actress Farrah Fawcett. Then came her failed six-year marriage to McEnroe, 43, toward whom she remains openly hostile. Worst of all is the loss of her children Kevin, 16, Sean, 14, and Emily, 11: When O'Neal became a heroin addict in 1995, McEnroe took custody of their kids and has retained it ever since. "Not being able to see my kids is like part of me is missing," a recovering O'Neal, 38, tells the magazine. "Part of my soul is missing."

Check out our photo gallery of Tatum O'Neal's life and times.