Like thousands of other street children of the favela underclass, he has had to steal and fight to survive, developing a tough outer shell.
At 13 he is still illiterate, with a drug habit, a vivid imagination, and no prospects.
Enter French pedagogue Margherit.
Determined to crack his defences, she insists on hearing his story.
As the two struggle to understand each other, Roberto discovers his first book, Twenty Thousand Leagues Under the Sea.
The book takes him to another world - "Like sniffing paint thinner", he says.
Her persistence in unravelling his story will put a check on Roberto's disbelief in his future, and will challenge Margherit about her own beliefs.
Can the power of love and affection really alter reality?
Paulinho Mendes, as Roberto, gives an entirely believable and compelling performance.
While at times gritty, the film never wavers in presenting hope as an option, and an undertone of humour and fantasy continually rescues the audience from despair.
Thankfully, the institutions designed to give the children of poverty-stricken families "a better life", like the one depicted in the film, no longer exist in Brazil, but the problem of children in poverty still exists, and the film asks hard questions about how these children can be helped.
The Story of Me screens at the Davis Lecture Theatre, Whanganui Regional Museum, Watt St, on Tuesday October 24 at 7pm. Entry is free, koha appreciated.
