Author and motivational speaker Liz Murray was born to drug-addicted parents in New York. Yet, against all the odds and without a roof over her head, she returned to high school at 17 and went on to win a scholarship to study at Harvard. She told BBC World Service's Outlook her remarkable story.
Liz Murray was only three years old when she realised her parents were hooked on drugs.
Several times during the day they would disappear behind a door, spread out the required tools across the table, and shoot up.
It was not long until this thin attempt at secrecy unravelled, and Liz, along with her older sister Lisa, was surrounded by addiction, living in filth and almost constantly hungry.
As a pre-school child, only the monthly welfare cheques brought some respite to Liz's life, and she would eagerly wait with her family as the postman approached.
"We would cash the cheque together," she recalls.
"My sister Lisa and I, we would walk them down to the drug spot, and Mom and Dad would go - they'd disappear up this staircase, they would buy drugs, and come back down."
Only later would the essentials be bought - usually just $30 spent on food for the entire month.
"We would do things like eat ice cubes, or chapstick or toothpaste. We would knock on our neighbours' doors.
"But everyone in the neighbourhood was living off government cheques."
Despite the wreckage her parent's drug addiction had caused, Liz was always grateful for her family life.
"I remember a certain peace in knowing we all went to bed under the same roof at night.
"My mother used to sit at the foot of my bed and she would share her dreams with me."
'Not a monster'
As her mother's desperation for money increased, that close bond was pushed to breaking point when Liz's grandmother sent her a birthday card containing $5 - only for it to be stolen by her mother to buy drugs.
But after Liz confronted her, her mother flushed her drugs away.
"She began begging me to forgive her. This is a woman who is strung out and desperate to get high - and she just flushed her drugs down the toilet.
"She looked at me and said, 'Lizzy, I'm not a monster. I just can't stop. Sweetheart forgive me.'"
Liz later found out that her parents had been sharing their needles with other addicts and, in 1990, her mother was diagnosed as HIV positive.
"You can only live this way for so long before something happens," she says.
With a mother in and out of hospital, and a father who was still heavily addicted to heroin, Liz eventually ended up on the streets.
In 1996, just before Christmas, Liz's mother died.
"She was alone when she passed away. We buried her in this service - they donated a pine box. Someone took a black magic marker, they misspelled her name."
Her mother's death inspired Liz to change her life.
She decided go to high school, even though she was still homeless. After many rejections, she finally opted for an "alternative" high school - Humanities Preparatory Academy in Chelsea, Manhattan.
Liz was beginning high school at a time most teenagers were graduating, but she promised herself to become a "straight-A student".
"In a world of 'no'," Liz remembers. "These teachers were a 'yes' to me."
As she neared the end of her high school education, and with her straight-A grades, Liz was taken on a school trip to Boston - her first time out of New York.
"The last thing we did was go to Harvard Yard, simply because we were supposed to take a picture in front of the John Harvard statue."
Sensing her excitement, a teacher suggested she apply but, with no money, and still homeless - a secret she had kept from everyone at school - Harvard seemed out of reach.
"I knew I needed scholarships," she says. "Finally, there was one from the New York Times. $12,000 per year, every year of school."
For the scheme, Liz had to detail what "obstacles" she had faced in order to achieve academically.
For many of her friends and teachers, it was the first they had heard about her past struggles.
"I remember coming in [to school] and the lobby was filled with people.
"They didn't know each other. They were people who read the article, got in their cars, drove to the school… 'Can we help Liz?'"
She never slept rough again.
With the scholarship money coming her way, Liz started her studies.
While she was there, she began public speaking - helping people who, like herself, had an almost impossible mountain to climb to succeed in life.
Now she makes her living as a motivational speaker and founder of Manifest Living, a company which offers workshops for people wanting to change their circumstances.
By the time she had finished her studies, Aids had taken the life of her father. Travelling back to take care of him, Liz says she took some comfort in knowing that her father had died a sober man.
"When someone gets sober, it's almost like meeting them for the first time.
"Just before he passed away, he wrote me this card.
"He wrote in the card, 'Lizzy, I left my dreams behind a long time ago. But I know now they're safe with you. Now we're a family again.'"
You can listen to the full interview with Liz Murray on Outlook from the BBC World Service.