The doctor has been extracting organs from deceased (and sometimes still-living) players in exchange for information on upcoming games.
While the players try to rest, a sub-plot involving a rogue group of guards and the doctor (Player 111) reaches a boiling point: Watch TV series Squid Game S1 E5 - MyFlixer
The guards recount a horrifying story of a woman they raped while she was unconscious on the operating table before she "sprang back to life". The doctor has been extracting organs from deceased
The episode ends with the old man, Oh Il-nam, in a state of heartbreaking vulnerability having soiled himself during the night, a weakness that makes him an immediate target in a "fair" world that only values strength. Squid Game Episode 5 Recap: A Fair World - Collider Squid Game Episode 5 Recap: A Fair World
Gi-hun looks at his raw, bloodied hands, realizing he has directly killed others to survive.