The fourth episode of Cashero begins with Sang-ung leading his bodyguard into a pond. The situation is still too close for comfort, and he is frustrated that when one needs money the most, it's nowhere to be found. Fortunately, Sang-ung knocks him out with wishing coins in the pond. Right then, Won-do calls Sang-ung and makes a deal - he wants to buy Sang-ung's superpower for whatever amount he wants. He even puts into effect a temporary truce, and Sang-ung is conflicted.
Once everyone is gone, the cops show up to investigate the destruction. Detective Hwang once again notices the coins and finds Sang-ung's loan agreement with Jeong-ja. The cops also realize that he is married to Min-suk, the witness from the hotel.
Sang-ung goes home to formally invite his parents to his wedding. Once his mom goes inside, Sang-ung confronts his father about the Mundane Vanguard. Dong-gi doesn't care if Sang-ung takes up Won-do's offer but warns him that the Vanguard cannot be trusted. Sang-ung is upset by his blasé attitude and tries to tell his father that he hurt him as a kid. He doesn't, but it seems that Dong-gi knows this.
Sang-ung needs a sounding board and decides to visit Eun-mi. While she is her brash, mocking self, she is actually a good choice. It turns out that Hwa-jin told her that all superheroes have sold their power to the Mundane Vanguard except them. And Ho-in knows this, yet he has been keeping it a secret from them.
Eun-mi and Sang-ung break into Ho-in's safe and find some files on the matter. Sang-ung is annoyed to learn that his kid will inherit his power no matter what. There is another file which records the amount the former supes sold their power for. Eun-mi is shocked that Hwa-jin sold hers for 80 million won. However, she is confused that these former supes never tried to contact her again. The file also has a record on Sang-ung - he is worth 1.3 billion won and he is highly likely to betray the supes. Sang-ung is upset by this observation.
It's a heart-wrenching revelation for Ho-in when he discovers he has liver cancer and realizes he doesn't have much time left. Despite this, he continues to indulge in alcohol and harass Eun-mi.
At the Jo household, Won-do is furious with Anna for failing to capture Sang-ung. Desperate and willing to do anything, he's ready to buy Sang-ung's powers before the boy discovers a loophole that involves his abilities. Anna tries to make things right, but Won-do refuses, claiming that "he" is returning from the US to take over. Anna is denied dinner and told to earn her meal by finalizing the sale of Sang-ung's powers.
Sang-ung decides to be selfish for once and demands 4 billion won in exchange for his powers. Won-do agrees, and Sang-ung is thrilled. He buys Min-suk expensive ice cream, takes her around the city using his superpowers, promises to buy her a nice apartment, and gives her a diamond ring. She's worried but agrees to trust him.
The next day, his good mood continues as he goes out of his way to help everyone. At work, he gets a new customer - Jo Nathan from the US. Nathan claims he's going to change the world and then brushes it off as a joke. Sang-ung doesn't think much of it until Detective Hwang shows up. Scared that he'll be imprisoned for the two incidents, Sang-ung runs off and tells Won-do to finalize the sale instantly. He makes his way to Beomha Ranch. Jeong-ja's men have been tailing him and watch from afar as he arrives at the lab's compound.
Ho-in and Eun-mi show up as well, but for different reasons. Ho-in tries to stop Sang-ung, claiming that it's a betrayal and a weakness to sell one's powers. But Eun-mi is upset that Ho-in kept everything a secret. Ho-in gets drunk to stop the sale, and a fight breaks out with Eun-mi backing Sang-ung. Jeong-ja's men try to grab Sang-ung but accidentally break the gate. In the chaos, Sang-ung makes it inside the lab. Anna brings out the money and mocks him for having no morals. Sang-ung starts to rethink his decision and is nervous as he's strapped to a chair. Before the extraction tool can enter his head, Ho-in shows up with a sniper rifle and shoots at him.
