Shani Krebs didn't fall in with a bad crowd – he was the bad crowd. Born to Hungarian refugees in Johannesburg, South Africa, Shani had a tough childhood. During his national service he started dabbling in drugs and it wasn't long before he was supplying the Johannesburg party scene with marijuana, LSD, mandrax and cocaine. It was a wild life, filled with girlfriends, narrow escapes and drug binges. His closest friend was his pistol.

Then, in 1994 at the birth of South Africa's democracy, Shani flew to Thailand where he was arrested for heroin trafficking and, after a trial, was sentenced to death. He was 34.

Shani's sentence was commuted to 100 years, and thus begun the greatest challenge of his life. The first hurdle was to survive in one of the toughest prisons imaginable: the random violence, the appalling diet, and the filth and diseases. Shani not only survived, he eventually rose to command significant respect within the prison system. The second was to stay off drugs after years of addiction. The third was nurturing a long-neglected spiritual side, which he found through his art and exploring his Jewish faith.

But what gave him most focus was, in collaboration with his sister Joan, trying to find some way either to be transferred to a South African prison or have his sentence shortened. He failed in the former but, after serving 18 years – the longest-serving Westerner in a Thai prison – he stepped off a plane at OR Tambo in 2012.

South Africa was a changed country, and Shani was a changed man. After adjusting to life on the outside, he is now a talented artist and public speaker, rallying against drug abuse in schools.

Dragons & Butterflies tells the remarkable story of a man who reached absolute rock bottom but had the fortitude to rise up again.