Professor Ouyang is unable to give Shen Wei any answers about how Doctor Feng Qübing cures his patients, but he does confirm that the results of his treatments are amazing. Later that night, they return to ask the doctor again to treat Zhao Yunlan.
Da Qing decides to spy on the doctor even though the man warned them numerous times that no one is allowed to watch him work. The second he realizes someone tried to sneak a peek, he kicks them all out and tells them not to return. (Good job, guys.)
After returning to the SID, the Chief tries his best to reassure his team and even to cheer them up a bit. But Shen Wei seems deeply troubled. It's no great surprise then, when Shen Wei visits Dr. Feng and once again asks the man for help.
Apparently still feeling all high and mighty after last night, the doctor agrees to help. But only if Shen Wei agrees to kneel down in repentance. (If only this guy knew who he was talking to!) Shen Wei forces himself to let his anger go for Yunlan's sake, and kneels outside the man's door in the pouring rain for hours until he's finally satisfied. (What a beautiful scene.)
Dr. Feng, at last, treats Yunlan's eyes and restores his vision. (Shen Wei is just so eager to see him after he's regained his sight, and both of them have these huge smiles of relief that it worked.) Seconds later, the Chief gets a call about a new case.
The crew mull over the mystery of several youths who turned into old men almost instantly. They realize that the victim who died used to deliver packages to their building. The Chief sends Xiao Guo and Lau Chu to interview the most recent victim, Liu Lang. When they learn nothing new, they go to talk to his coworkers and witness a man transforming right before their eyes.
Once again, the crew gather ‘round and share information about the case. It turns out all six victims have a connection to the same company. It seems most likely to be the work of dark energy, but when they try to verify, they realize none of their detectors are working. Even Shen Wei cannot currently sense dark energy. Zhu Hong realizes there's a connection between the company and Dr. Feng, and they decide to pay the doctor another visit.
The Chief wastes no time before confronting Dr. Feng with the evidence of how a new victim appears every time he treats a patient. The doctor explains how a man in a black hoodie came to him with a brush that could fulfill his dream of being a skilled doctor. He honestly had no idea that he was hurting people. He wants to make things right.
Finally, Dr. Feng has his moment of redemption when he sacrifices his own life force to return the years that were stolen from all of the surviving victims. Much to Shen Wei's dismay, Yunlan also returns the energy used to heal his eyes and is now blind again.
Meanwhile, Professor Ouyang calls Li Qian and asks her to come to visit his super-secret lab. They test her blood and see that it has been altered by her constant contact with the Longevity Dial. When she corrects some of their calculations, they realize she may be a viable substitute for Professor Shen and ask her to join the project.
Later that day, after the world's worst attempt at a heist on the lab, Sha Ya is revealed to be a full partner with Ya Qiang and the Merit Brush user.
The following morning, a letter is delivered to the SID taunting them that the Merit Brush owner will turn himself in if they can identify him. While they're still debating how seriously to take the letter, Lin Jing receives an anonymous email explaining how to heal Yunlan with the Longevity Dial. (That thing is turning into a Deus Ex Machina.)
Shen Wei, of course, wastes no time at all testing to see if the Hallow really can heal Yunlan. Although the Chief at first pretends it didn't work, they succeed on the first try. (Aww. The end of Yunlan constantly clinging to Shen Wei kinda makes me sad.) While the team celebrates, the Dial triggers a second time in Shen Wei's hand, causing him pain.
Back at their apartment, Shen Wei and Yunlan share a meal while the Chief drills his dinner mate for info on the Merit Brush. Unfortunately, even the Black Cloak Envoy doesn't know more than what's told in the legends. More unsettling though, he still can't detect dark energy anywhere in the city either. For help, he contacted the Regent who says there may be some useful intel in Dijun Palace. Yunlan insists on going.
At the doorway to Dixing, Da Qing appears and comes alarmingly close to attacking Shen Wei. Based on a terrifying flashback he had while under hypnosis, Da Qing now believes Shen Wei may be a threat and hijacks their portal in order to come along.
Thanks to Da Qing destabilizing the magnetic field, he and the Chief are separated from Shen Wei. By the time they are reunited and make their way to the palace, the Regent has declared the palace closed until after a new king is inaugurated, leaving them little choice but to stay overnight and wait.
“As long as you promise to help my friend, I'll do anything you ask.” Shen Wei
“I thought that after my vision returned, there wouldn't be any more happy days of ‘If I ask for food, then I get food’. I even considered staying blind for longer.” Zhao Yunlan
Episode 21 "Zhao's Blindness"
Episode 23 "One and Future King"