New specimens

Finding the base
Quests starts when Lust Doll finds Deserted Base while traveling between locations. After passing the Senses check, that location becomes accessible permanently.

Quarantine
While exploring the base, Lust Doll would notice two locked doors, one on the first, and one on the second floors, which prevent them from accessing the rest of the base. Fortunately, the second floor has a single chest with the key from door on the first floor.

Behind that door, there's a huge hole, which leads to the otherwise inaccessible rooms on the second floor. Jump into it when you are ready, but be warned: past that point, it's do-or-die: you would only return after you finish the quest.

Infestation
The first thing you would notice after jumping down is that the whole place is covered by weird pink meat "moss". Then Infected would start attacking you.

Being defeated by Infected would result in you being infected with meat parasites; males would infect you with chest parasite, females would infect you with crotch parasite. You can't be infected with parasite which you already have; you would just pass out instead.

Being defeated by any Infected while already having both types of parasites would result in you being fully infected, and abrupt Bad End.

Don't worry, there would be multiple opportunities to remove them later.

Lower floors
Here, infestation went so far, this place is barely recognisable by now. Besides Infected, there are several hidden meat tentacles which would try to grab incautious player, requiring to pass 20+(4*Nim)% Nimble check, or taking stamina damage on failure. Passing out due to this damage, or deliberately choosing to being caught would result in them stripping you naked, and grabbing somewhere. Any previously encountered tentacles (or those noticed by having sufficient Senses) would be marked on the map permanently.

Corridors here are linear. The far-most room would contain spawn points for Meat Tendrils (save one for now; the rest may be sold freely), and, more importantly, the chest which would contain the key from a locked door on the second floor, allowing you to leave.

The moment you would try to leave, you would be ambushed by the master of this place, Mistyra. Being defeated by her leads to you being captured; otherwise, you may proceed to the exit. Note that Mistyra would become a random encounter from now on, and can ambush you again for as long as you're on the third floor. Choosing to pursue her while being infected with meat parasites opens up additional scenes, and allows to remove them (regardless of outcome).

In capture
See also: Mistyra

If Lust Doll was captured by meat tentacles, or defeated by Mistyra, they would find themselves trapped in some meat trap, completely naked and with meat parasites attached.

Escape works pretty similar to any other grab, with player dealing some "damage" to hidden entity until they break free. With Nimble below 5 it seems to be impossible to escape in time, but each time they struggle, Nimble stat slowly trains, so eventually the player would accumulate enough to escape; but if they start with very low amount, it may take a while. Alternatively, if they possess Electroshock spell, they may spend 2 MP to escape immediately.

If Lust Doll fails to escape, or deliberately chooses to not resist, Mistyra would return and proceed to make fun with them, resulting in one of the four scenes (depending on which genitalia Lust Doll has, and which kinks are enabled). If they keep failing to escape, eventually additional unmarked scene would appear. Choosing it would lead to Mistyra making Lust Doll her permanent sex slave, causing Bad End; otherwise, the game proceeds as normal.

After escaping, Lust Doll must take the key and Meat Tendrils, and leave the same way you made it there.

New specimens
Once you have either meat parasites or Meat Tendrils, visit the Science Lab Tower in New Ark City, and talk with secretary on the first floor. They would tell you to go on the second floor and talk with the scientist called Linda.

If you're infected, Linda would take the meat parasites from your body and use them for experiments; if you're not infected, she would take one Meat Tendril instead.

After talking with Linda, procedure to remove parasites becomes available at any moment, free of charge.