It looked like any old envelope left behind in the back of a cab.
But when taxi driver Seng Kiah Chen took a closer look, he saw something that made his heart thump. The envelope was stuffed with thousand-dollar bills.
"I hadn't seen so much money before," he told The Straits Times. "My heart was beating very fast."
Mr Seng, 55, was one of three ComfortDelGro drivers who found nearly $70,000 in total in their vehicles last month.
It turned out that the envelope had been left behind by a passenger who wanted to be known only as Mr Cheah. After hailing the cab on June 27, he got out at his Geylang office without realising that the envelope had slipped in between the rear seat and door.
Mr Seng then ferried another passenger, before getting out of his taxi to tidy it and responding to a booking.
When he opened the rear door, an envelope dropped out. To his shock, it contained the wad of bills - $45,000 in all. Shortly after that, Comfort's lost and found department contacted him.
Not knowing which passenger had left the money in his cab, he returned it to the company's office in Sin Ming after completing his booking job.
Mr Cheah was overcome with relief when the cash was returned to him. "He kept thanking me," said Mr Seng.
"He said he wanted to use the money to pay his workers' salary, and that his hands were shaking when he called the lost and found (department) as it wasn't his own money.
"I told him he was very lucky that the earlier passenger did not see the money and take it."
Both of the other lost-and- found cases were on SBS Transit buses. Driver Lee Choy Yoong, 55, was checking her bus on June 22 when she found a plastic bag with more than $18,000 in bank notes.
Mr Valaiyapathi Doraimahalingam, 50, was driving service 74 when he spotted a black backpack on a seat near the front of the bus through his rear-view mirror.
It contained a China passport and a wallet with $5,350 inside. In both cases, the money was returned to its owners.
ComfortDelGro spokesman Tammy Tan said all three drivers had "upheld the group's key values of honesty and integrity, despite what may have proven to be a huge temptation to some".
She added: "They have done us proud."
Last year, Comfort cabby Sia Ka Tian made headlines for finding and returning $1.1 million to a Thai couple holidaying here.
More than 60,000 lost items were found last year in the company's taxis, buses and trains, and at its interchanges and stations. They ranged from wallets to bags to mobile phones.