In 1978, Roberts was sentenced to a 19-year imprisonment in Australia after being convicted of a series of armed robberies of building society branches, credit unions, and shops. In July 1980, he escaped from Victoria’s Pentridge Prison in broad daylight, thereby becoming one of Australia's most wanted men for the next ten years.
The protagonist Lindsay (according to the book, Roberts' fake name) arrives in Mumbai carrying a false passport in the name of Lindsay Ford. Mumbai was supposed to be only a stopover on a journey that was to take him from New Zealand to Germany, but he decides to stay in the city. Lindsay soon meets a local man named Prabaker whom he hires as a guide. Prabaker soon becomes his friend and names him Lin (Linbaba). Both men visit Prabaker's native village, Sunder, where Prabaker's mother decided to give Lin a new Maharashtrian name, like her own. Because she judged his nature to be blessed with peaceful happiness, she decided to call him Shantaram, meaning Man of God's Peace. On their way back to Mumbai, Lin and Prabaker are robbed. With all his possessions gone, Lin is forced to live in the slums, which shelters him from the authorities. After a massive fire on the day of his arrival in the slum, he sets up a free health clinic as a way to contribute to the community. He learns about the local culture and customs in this crammed environment, gets to know and love the people he encounters, and even becomes fluent in Marathi, the local language. He also witnesses and battles outbreaks of cholera and firestorms, becomes involved in trading with the lepers, and experiences how ethnic and marital conflicts are resolved in this densely crowded and diverse community.
The novel describes a number of foreigners of various origins, as well as local Indians, highlighting the rich diversity of life in Mumbai. Lin falls in love with Karla, a Swiss-American woman, befriends local artists and actors, landing him roles as an extra in several Bollywood movies, and is recruited by the Mumbai underworld for various criminal operations, including drug and weapons trade. Lin eventually lands in Mumbai's Arthur Road Prison. There, along with hundreds of other inmates, he endures brutal physical and mental abuse from the guards, while existing under extremely squalid conditions. However, thanks to the protection of the Afghan mafia don "Abdel Khader Khan", Lin is eventually released, and begins to work in a black market currency exchange and passport forgery. Having traveled as far as Africa on trips commissioned by the mafia, Lin later goes to Afghanistan to smuggle weapons for mujahideen freedom fighters. When his mentor Khan is killed, Lin realizes he has become everything he grew to loathe and falls into depression after he returns to India. He decides that he must fight for what he believes is right, and build an honest life. The story ends with him planning to go to Sri Lanka, which lays the premise for the sequel to this book.
While parts of the novel, based on Roberts' known biography, read as reportedly factual, numerous significant claims by Roberts are impossible to verify and are disputed by the family of one of the main Indian characters in the book. A few parts of the story, such as Roberts' criminal history and escape from prison in Australia, are a matter of public record, while others remain harder (or impossible) to verify.
There is a great deal of debate as to where the boundaries lie between fact and fiction in the book. Roberts has stated the characters in the story are largely invented, and that he merged different elements taken from true events and people into such events and characters like Prabaker 'of the big smile'. Prabhakar Kisan Khare was a real-life individual, as are the members of Khare family from the book (Kisan, Rukhma, Kishor and Parvati Khare) whose names appear on government issued identity cards. The family resides in the Navy Nagar slum where the lead character Shantaram also lived. The Khare family disputes many of Roberts' claims, although they acknowledge close association with Gregory Roberts in the 1980s. Prabhakar died in an accident in 1988 in circumstances matching the event in the book. In March 2006, the Mumbai Mirror reported they may have discovered the inspiration for the big smile of the character Prabhakar as belonging to a still living cab driver called Kishore, who took Roberts to his home village. Kishore Khare, brother of Prabhakar, who drives tourists around Mumbai, has told his story.
Roberts' position, based on his interviews
"With respect, Shantaram is not an autobiography, it’s a novel. If the book reads like an autobiography, I take that as a very high compliment, because I structured the created narrative to read like fiction but feel like fact. I wanted the novel to have the page-turning drive of a work of fiction but to be informed by such a powerful stream of real experience that it had the authentic feel of fact."
"As with the novel Shantaram, the experiences in The Mountain Shadow are derived from my own real experiences, and the characters, dialogue, and narrative structure are all created."
Roberts repeatedly stated this, as on the book's official website:
"All of the characters in the novel, Shantaram, are created. None of the characters bears even a remote resemblance to any real person I’ve ever known. Proceeding from the theme of exile, all of the characters represent one or another aspect of the exile experience. None of the characters – with the exception of Johnny Cigar, who is born to a vanished (exiled) father from somewhere beyond the city – is born in Bombay." 
Khare family's position, based on their website
Kishore Khare, younger brother of Prabhakar, one of the main Indian characters in the book states that important parts of Robert's "personal facts" are simply untrue:
"Some parts of his story are absolute facts and a narration of real-life events. But there are others that are fiction. Gregory lived in the slums a life of crime and drug addiction. My family cared for him and rescued him from his addiction. There was never a clinic that he ran in the slum or treated anyone for anything. He did not buy Prabhakar a taxi as the book claims. Sadly, Karla was also a drug addict who eventually died on the street in the massive AIDS epidemic of the 1980s.
The narrative on gun running for Afghan Mujahideen against Soviets also cannot be true. Gregory was in Mumbai until the early 1990s, still deep in addiction. The Soviet war in Afghanistan ended in 1989."
"Gregory, meanwhile still lives in Mumbai, elevating himself to a long-term residence of a luxury hotel. Every now and then he shows up in our slum with celebrities – Oprah, Madonna, Johnny Depp while his “slum guards” keep the slum dwellers from protesting his presence and his lies."
This webpage has been deleted from Kishore's website as of 3/29/2015.