Episode Summary
Bai Enyu clashes with Lin Zhitao over a case, while Lu Sheng returns to crime due to family issues and gets caught. Lin Zhitao investigates the exploitation of underage criminals. Bai Enyu suspects Lu Sheng is covering for someone and, with Lin Zhitao, investigates, eventually uncovering the real criminal operation.

Spoiler Alert
Episode 4 Recap & Spoilers: A Descent Back In
Okay, so Episode 4 gets pretty heavy. We see Bai Enyu, already wanting to head home after a long day, gets roped into assessing Huang Jiawang alongside Lin Zhitao. Bai Enyu's got this bias against Lin Zhitao, thinking she was too lenient during Huang Jiawang's original sentencing. He basically takes out his frustrations on Lin Zhitao after bringing Huang Jiawang back in. Drama!
Meanwhile, Lu Sheng, fresh out of prison, walks back into a nightmare. His dad's a drunk, his mom's struggling with her mental health, and his little brother's being forced into petty theft by their uncle. Desperate, Lu Sheng falls back into his old ways, only to get caught in a police sting. Talk about a rough reentry.
This sting operation brings in a bunch of underage kids, which is where Lin Zhitao and her assistant, Cheng Wei, come in. They're on the scene early because the prosecutor's office just launched a juvenile division. On the home front, Bai Enyu's wife is understandably upset, lamenting that she barely sees him and worried about raising their son alone. Bai Enyu, feeling the guilt, tries to get some slack from his boss, hoping to at least make it home more often.
Then, Bai Enyu hears Lu Sheng's been picked up again and rushes to the station. He's shocked – Lu Sheng was one of his star students! He confronts Lu Sheng, who initially seems nervous but quickly claims he's the mastermind the police have been hunting. The cops aren't buying it. They've got evidence pointing to a more sophisticated operation: a pregnant woman as the initial decoy, kids swiping cash from registers, elaborate escape routes with multiple bus transfers to avoid surveillance. This isn't the work of some newly released ex-con.
Because of her pregnancy, the woman is released. The children are released too, after a warning, due to their young age. Lin Zhitao is heartbroken when she sees the state of some of these kids, some as young as three or four, covered in bruises and clearly traumatized. The counselors are deeply worried about their futures. One little girl, terrified of Lin Zhitao, begs not to be put back in a cage, promising to be good. It's seriously messed up.
Bai Enyu refuses to believe Lu Sheng is the real culprit, convinced he's covering for someone. Lin Zhitao and Bai Enyu decide to investigate Lu Sheng's home. They find Lu Sheng's mom in a confused state and his dad deep in his cups. Bai Enyu pretends to be a friend of Lu Sheng's and gets Lu Guangfu (Lu Sheng's father) talking over drinks. This leads them to some crucial information, and they finally track down the real criminal ring's hideout.