A shopper buying boots from New York department store Saks Fifth Avenue was left shaking after finding a note from a man claiming to be held unfairly in a Chinese prison factory.
The handwritten message began "HELP, HELP, HELP" and went on: "We are ill-treated and work like slaves for 13 hours every day producing these bags in bulk in the prison factory."
It ended: "Thanks and sorry to bother you."
The note was signed Tohnain Emmanuel Njong and accompanied by a passport photograph of a man wearing an orange jacket.
Stephanie Wilson, 28, an Australian who lives in Manhattan's West Harlem, who found the letter after buying Hunter rain boots in Saks Fifth Avenue in September 2012, told DNAinfo New York: "I read the letter and I just shook. I could not believe what I was reading."
Wilson passed the message on to the Laogai Research Foundation, a Washington DC non-profit organisation which highlights human rights abuses in Chinese prisons, which in turn turned it over to the Department for Homeland Security to investigate the claim of forced labour.
However, a Yahoo email address written on the back of the letter turned out to be defunct and the prisoner's fate remained a mystery until DNAinfo New York tracked him down via social media this month.
The Cameroon national, who is now 34, said he had been teaching English in the southern Chinese city of Shenzhen when he was arrested in May 2011 and charged with fraud.
He denied the charge but was convicted 10 months later and sent to prison in the eastern city of Qingdao, Shandong Province, where he was banned from contact with the outside world and forced to work long hours, sometimes making bags such as the one for Saks Fifth Avenue and at other times manufacturing electrical parts.
In total, Njong said, he wrote five letters using a pen and paper given to the prisoners to record their output. "We were being monitored all the time," Njong said. "I got under my bed cover and I wrote it so nobody could see that I was writing anything.
"Maybe this bag could go somewhere and they find this letter and they can let my family know or anybody [know] that I am in prison."
Finally released after three years and put on a plane back to Cameroon, where his family had assumed he was dead, Njong is now living in Dubai, where he has secured a new teaching post.