There was a clever merchant who ran a small shop.
有一个聪明的商人，经营着一间小小的店铺。
His shop was always busy, with customers coming and going.
他的店铺生意一直不错，顾客络绎不绝。
However, the merchant had a secret that no one knew.
但是，商人有一个不为人知的小秘密。
He had a tacit cooperation with a supplier.
他和一位供应商有着默契的合作关系。
Whenever the merchant needed goods, the supplier would always prepare them in advance.
每当商人需要货物时，供应商总是提前准备好。
And when the goods arrived, the merchant would raise the price a bit.
而商人则会在货物到达时，把价格抬高一些。
In this way, both the merchant and the supplier benefited.
他们这样做，双方都从中得到了好处。
The merchant's shop seemed to be thriving, but the customers didn't know the truth.
商人的店铺看似生意兴隆，顾客却并不知道真相。
One day, another competing merchant discovered this situation.
一天，另一位竞争商人发现了这个情况。
He decided to report their collaboration to the authorities.
他决定向有关部门举报他们的合作。
Investigators began to check the merchant's books and transaction records.
调查员开始检查商人的账本和交易记录。
Soon, they discovered the issue with the merchant and the supplier’s transactions.
很快，他们发现了商人与供应商之间的交易问题。
The merchant and the supplier’s actions were exposed and punished.
商人和供应商的行为被揭露出来，受到惩罚。
Their secret cooperation was no longer a secret, and in the end, both lost the trust of others.
他们的合作变得不再秘密，最终两人都失去了信任。
"Colluding for personal gain" means an improper cooperation or secretly manipulating things for personal advantage.
“上下其手”这个成语，字面意思是上面和下面互相合作。
This idiom refers to unfair collusion or secretly pulling strings behind the scenes.
它的意思是指不正当的勾结或暗中做手脚。
