How to get this quest
You get this quest automatically when entering Nephlune.
Trust mechanic
If you enter Liliana's house, she will introduce you to a path leading to an underground pub. Getting there will introduce you to Trust counter appearing while disguised as Mary. Gaining trust allows to progress inside the underground city and access some bonuses. Here are the main checks allowing to progress in the quest:
- 20 Trust to go freely from the pub to the underground city,
- 60 Trust to go through the worshipper guarding the west part of the city,
- 80 Trust to make the guardian to James' quarters free your path,
- 100 Trust to let James give you access to his study, allowing you to complete the quest. Note that having Shadowcloak on allows you to sneak by him.
Here are the bonuses you can get by gathering enough trust:
- 40 Trust for the worshipper guarding the secret stairs going outside the city to let you pass,
- 50 Trust to learn the rank I spells from the underground spell shop,
- 70 Trust to persuade the worshipper guarding two abductees to let them go,
- 90 Trust to make two worshippers inside James' quarters let you access some loot,
- 100 Trust to learn the rank II spells from the underground spell shop,
- 150 Trust to learn Horror III from James after giving him the Humanitas rune and waiting 20 days.
Here are the opportunities to gain trust:
- Inside the pub, there is a drug maker asking first for 5 ethers, then 3 mutated spores, and finally 1 scorpio claw. You gain 5 Trust for each request you complete. Talking to him after completing his three requests also yields you 2 Sweet Memories drugs.
- Working as a waitress with the normal outfit yields you 1 Trust. This is repeatable.
- Working as a waitress with the sexy outfit yields you 2 Trust. This is repeatable.
- Working as a waitress with the bunny outfit yields you 3 Trust. This is repeatable.
- The Costumer Service 1 lewd scene yields you 3 Trust.
- The Costumer Service 2 lewd scene yields you 4 Trust.
- The Costumer Service 3 lewd scene yields you 6 Trust.
- Completing Demon Worshipper 101 yields 10 Trust in total (or 13 if you find the secret answer).
- Selling a drug formula to the drug dealer yields 5 Trust.
- In the northern part of the underground city, you can find a hooker. Talking to her allows you to pay 200 G and gain 1 Trust. The NPC blocking a rope point will also move, allowing you to access the western part of the city without being blocked by the guardian.
- Learning Acedia from the magistrate who gave you the knowledge test yields you 10 Trust.
- The first lewd scene with the drug dealer yields you 3 Trust.
- The second lewd scene with the drug dealer yields you 5 Trust.
- The third lewd scene with the drug dealer and its repeatable version yield you 8 Trust.
- There is a worshipper near the pub's door (the one facing water). Giving him 10 mana stones yields you 5 Trust.
- There is a magistrate worshipper living in a house west of the underground city. If you are wearing the bunny outfit, he proposes up to two lewd events. Both of them yield 10 Trust.
- Talking to James about magic unlocks a dialogue option about runes. Once this option is taken, you can give him the Humanitas rune and gain 20 Trust.
- Clearing the rubbles during Demon-cracy gives 5 Trust.
The secret path to the underground city
In Neplune's undergound, there is a cracked wall near the southwest stairs. Destroying this wall (with 5 bombs, 1 bomb+, or collar removal) leads to a path ending up with a slime summoner worshipper. This enemy is accompanied by two water mage worshippers. Behind this enemy encounter, there is a whole serving has the secret entrance to the underground city.
The first time you enter through the secret entrance, you will be undisguised. But, if you are familiar with the underground pub, every subsequent entrance will give you the option to disguise.
While undisguised in the underground city, all worshippers turn into enemies and you can't cross any door except the one leading to James' quarters. You can make you way to James' laboratory by fightning, sneaking, or using flash bombs. You can sneak past James by using Shadowcloak, use a flash bomb or fight him.
Note that there are candles on a wall in James' quarters. If you fight James near those candles, the phantoms he summons will get affect by their light sensitivity.