Madam Ng Lye Poh was walking home alone from a market when a man approached her to say her son was suffering after a bad fall.
He offered to take her to see him and the worried 79-year-old agreed to get in his car.
It was about 11am on Wednesday. The man took her from Hougang Avenue 2 (not Hougang Avenue 8 as previously reported based on what the police said) to a location unknown to her where she was tied up and blindfolded,beginning a kidnap ordeal lasting more than 12 hours.
At about 1pm the kidnappers called Madam Ng's son, Mr Lim Hock Chee, on his mobile phone to ask for a ransom of $20 million.
"The caller told me that my mother is in his hands and let me hear my mother's voice," said the 52-year-old chief executive officer of Sheng Siong supermarkets.
"At first I thought it was a scam because the person had called my mobile phone. I called my mother but the line was engaged. I called my maid at home and told her to call my mother. She also couldn't get through."
It was only then that Mr Lim realised that his mother had actually been kidnapped.
"The kidnappers threatened to hurt my mother if they didn't get the money," Mr Lim told reporters at a press conference yesterday at one of his supermarkets at Block 720 Clementi West Street 2.
"I was shocked. When such things happen, of course we would be frightened. But we tried to remain calm and solve it."
Mr Lim, who has eight siblings, decided to discuss the matter with his elder brother Lim Hock Eng, 53. Both agreed to call the police.
Police said they received a call from Mr Lim Hock Chee at 2.13pm, sparking immediate investigations by the Criminal Investigation and Police Intelligence departments.
Mr Lim said he received about 30 calls from the kidnappers throughout the day - though there was an hour or two when he heard nothing.
"Police helped to calm me down and taught me how to negotiate with the kidnappers," said Mr Lim in Mandarin.
He managed to negotiate the ransom sum to $2 million - but did not say how, citing ongoing investigations.
Before midnight yesterday, Mr Lim drove to Sembawang Park alone where he dropped off the ransom money, packed in a bag, under a tree.
Twenty minutes later, he received a call from the kidnappers informing him that his mother had been left in the Seletar West Camp area.
Police later found Madam Ng at a bus stop in Seletar Aerospace Drive and took her to Khoo Teck Puat Hospital for a check-up.
Within an hour or so after Madam Ng was released, police had tracked down two suspects. They were arrested separately in Hougang and Ang Mo Kio.
Police also recovered the $2 million ransom money from under a tree in the vicinity of carpark 2 of Sembawang Park.
Last night, outside Mr Lim's home, his elder brother Mr Lim Hock Eng told The Straits Times that Madam Ng was still "in a bit of shock". She had been discharged from hospital at 5am yesterday with doctors saying she was fine.
The family declined to let reporters speak to Madam Ng, saying she was resting at home.
Neighbours described Madam Ng as friendly and humble.
"She looks quite modern but she does not wear much jewellery or flaunt her wealth," said one, who declined to be named. "In fact if my other neighbour did not tell me, I wouldn't have known her son owns Sheng Siong supermarket chain."
The Straits Times understands that supervisors of at least eight Sheng Siong outlets received an internal memo after 6pm yesterday, advising them to say they knew nothing if approached by reporters.
News of the kidnapping spread among the supermarket chain's outlets. Staff said they were shocked, even though they knew little of Mr Lim's family. They did not know of any Sheng Siong employees who fitted the profile of the suspects.
Police identified one of the suspects as a 41-year-old odd-job labourer sub-contracted to a supermarket and the other as 50-year-old credit card promoter.
Additional reporting by Hoe Pei Shan