One day, a dead body is found at an apartment near the supermarket. Finding this murder odd, Dae-sung, his mother, and his girlfriend Ah-hee gather around to find the real murderer, starting by looking through the receipts of the market.
Daesung Mart develops into the great MS Mart thanks to Myung Sook’s bravery and Dae Sung’s smartness. Although Dae Sung continuously fails the civil service exam and is about to get dumped by A Hee, his love for his mother’s supermarket does not change. He determines to work there as a cashier, but runs into a case that changes his life as an employee of MS Mart.
The police begin investigating the body that Dae Sung and Nunchucks Grandpa found. However, Dae Sung becomes nosy again and starts digging into this by himself. His way of investigation is looking into the shopping list of the victim. With the clues that he obtains from there, he notices a suspicious person within the neighborhood.
People now know that Nunchucks Grandpa is the notorious five-dollar bill counterfeiter. Although some evidence show that Five Dollars is the murderer, it is not enough to prove his guilt. Dae Sung is upset that the counterfeiter might be set free. However, he witnesses someone else at the murder scene who definitely seems suspicious.
Five Dollars eventually becomes free from being a suspect. However, the police now suspect Dae Sung. To clear his name, A Hee, Dae Sung, and Myung Sook investigate everyone in the neighborhood. Currently, although their biggest suspect is Fish, Products also seems to be very busy right after the murders occurred. With every possibility in mind, the supermarket investigation begins.
Five Dollars finds and takes what Yul hid in her secret place. But the chairwoman finds the two and saves Yul from the criminal. As many people now think Five Dollars is not the killer, new suspicions lead to someone within the supermarket. Seeing how Veggie seems to be the new target, Meat becomes the number one suspect. Although Dae Sung does not want to believe so, Meat must be investigated.
The chairwoman miraculously survives the fall. Although she is in horrible shape and in a coma, she provides a clue to Products. Meanwhile, Veggie is still going through a hard time. Even though there is no clear evidence, everyone strongly believes that Meat is the one harassing her. However, new events occur and bring up new information regarding the murder cases.
As Products has been acting suspiciously, Dae Sung and Myung Sook tail her to see if she is the killer. However, Products is not the only suspicious one. Although it is clear that Yul is being abused by her father, she denies help. Dae Sung tries to think why Yul is denying help and confidently says that Dae Sung is not the murderer. This allows him to come up with another lead.
Now that Cheon Kyu stabbed the detective, it is certain that he is the murderer. He then flees with Yul where no one can find them. However, Yul comes up with a clever idea to give a clue to Dae Sung. Without any help from the police force, the employees of MS Mart rush over to save Yul from her father. The hostage situation is dangerous, but everyone risks their lives for Yul.
