In the Mouth of Madness is the first chapter of the Black Lagoon spinoff series Dismemberment Galore! The Gore Gore Girl. It was originally released on September 19, 2019.

Sitting on the toilet in Shenhua's apartment, Sawyer the Cleaner slouches down, and a voice asks her how long she has been in the bathroom. As she drinks a glass of tea with medication to help her bowel movement, the voice, revealed to be Lotton, advises her not to mix her medication with his grandmother's medicinal tea, saying that she will be in trouble if she does so. Dropping the bottle of pills, Sawyer crouches her head down in anguish, and she hears another voice claim that she is a sorry sight. Looking at the wall, Sawyer sees the housefly, who asks her if she recognizes the bug, clarifying that it is one of the maggots who wanted the corpse that she cleaned up three days ago. As Sawyer sweats, the fly then buzzes around, and Sawyer hears a third voice from the adjacent shower. The shower silhouette asks her if she still has his eye, requesting her to dispose of it immediately. Sawyer hears a knock on the door from another voice that tells her to hurry up.

While the shower hallucination laughs and freaks Sawyer out, the housefly and other voices in her head taunt her. As all of the noises rush to her head, the housefly and corpse hallucination suddenly become happy and positively encourage Sawyer, singing a song about bowel movements. The singing continues and Sawyer smiles at the song, giving her best effort and soon succeeding in finishing her business, extending her arms upward in joy. Outside the bathroom, Shenhua and Lotton wait, with the former hoping that Sawyer is not cutting her wrists again. Yelling at Sawyer, Shenhua tells her that her bathroom better not be covered in blood, but Sawyer opens the door and comes out, showing a blank face to the two freelancers as if nothing happened, walking away happily.