The scammers knew exactly what strings to pull. They had overheard Mrs La's concerns about her sons and her worries about them driving on Vancouver's streets during the rainy seasons, and they used those fears and superstitions against their victim.

It is a scam that has kept five Chinese nationals, in Canada on visitors' visas, behind bars since July 15, when they were stopped trying to leave Vancouver airport for Hong Kong with C$148,000 (HK$1.1 million) in cash and enough hidden jewellery to make border agents suspicious.

La, who doesn't want her full name used, tells Post Magazine that some of that cash and jewellery belongs to her.

She didn't think anything of it when a fellow passenger on a Vancouver bus asked her whether she knew how to locate a famous Chinese doctor. When she said no, another passenger piped up and told them she knew exactly how to find the man.

Her interest piqued, La got off the bus with the other two women to seek the doctor. They encountered, in an alleyway, a third woman, who told them she was the doctor's granddaughter.

"She knew right away many things about me," says La. "She knew about my sons. She knew my name even."

La found out later from the police that the perpetrators on the bus had a wireless microphone, so the "granddaughter" could hear their conversation.

The "granddaughter" told La that one of her sons would be in a car accident unless she returned with valuables that the doctor could bless. Without thinking, La says, she went to her bank, withdrew her savings and jewellery and brought them back to the alleyway, where the three women were waiting. La was told to keep her items in a red bag along with some bottles of water that had been blessed by the doctor. The bag was sealed and La was told not to open it for two months.

But doubts grew and, a few days later, La opened the bag and, instead of her valuables, found only wads of paper.

Known as a "blessing scam", it's a con Vancouver police believe may have taken in dozens of Asian seniors.

There have been similar scams in San Francisco and New York, other North American cities with sizeable Asian populations.

La says the cash they took from her, about C$11,000, had taken her years to save. What's irreplaceable, though, is the jewellery she received from her mother, which she had planned to give to her sons one day.