The hidden guild recognizes Carl as a spider and family member when he passes through its covert entrance.
The Guild occupies a hot brick complex behind the Penis Parade's final private cubicle. Entering the boundary strips away Carl's privacy bubble and replaces the club's music with silence.
The system welcomes Carl as a spider and tells him he has come home. A web-carved wooden door at the corridor's end recognizes that he is already a member, then triggers the Molly Maguires achievement before admitting him to the main room.
The AI's commentary initially compares justified secret resistance against structurally unfair power to the Guild's existence, then abruptly denies the connection and calls the organization another religion-themed vehicle for a demigod seeking advancement.
A hot torchlit brick corridor ending at a plain wooden door deeply carved with a spiderweb.
The Guild is the secret society controlling Katia's assassination job and recognizing Carl's inherited membership.
Also appears in books you've already read — spoiler-safe to their endings: