![](https://pic1.mangapicgallery.com/r/avatar/68/u187394_50x50.jpg?2)
Take it with a grain of salt, as my understanding is entirely based off of shoddy google translating-ing, but...
Basically, Myeong-il has made a duplicate key for the office where the mail is stored. Jingi & Heonjae create a distraction by "fighting" when the guards are bringing Myeong-il back to the cell, so the guards leave him unattended at the end of the hall near the office while they try to break them up.
Once he's in, he starts snooping & notices files on everyone. He's reading one for Jingi & Heonjae, and finds out some of the awful things they've done to other inmates & their past "pigs". He also finds out that Heonjae killed someone in a really gruesome manner, but that it wasn't intentional (from other chapters, it seems like he has some sort of pain/injury kink, so maybe related to that?). Older entries in the file seem to indicate that Jingi was self-harming: cutting himself, swallowing objects so that they'd have to perform surgery to remove, not eating, etc...
Myeong-il finds out from the file that the guards have been throwing all of Jingi's mail away, so he's able to locate the most recent letter for him in the trash can. (There's a part where one of the guards leaves Jingi & Heonjae fighting to go get a camera from the office - they also file away videos of prisoner incidents - so Jingi starts yelling at them to retain their attention & keep them from finding Myeong-il).
Myeong-il manages to get back out of the office with the letter from the trash, undetected. He gives it to Jingi, noting that he puts it away rather than opening it immediately. He's kind of scared of Heonjae after reading about it. It ends with Heonjae asking him if they can have sex again. Lol. (Heonjae looking like a yandere this chapter... Poor Myeong-il.)
Can anyone spoil me what went on in chapter 24 please?