Rescue Sinthia

Save Sinthia is a side quest in Fallout.

Quick walkthrough
If the Vault Dweller spends a night in the Crash House Hotel in Junktown, they'll wake up to find the hooker Sinthia held hostage by a random raider in the room adjacent to theirs. Marcelles will beg the player to defuse the situation.

Detailed walkthrough
There are three ways to solve this quest.

Peaceful solution
As soon as the raider can see the player, he will start dialogue. When talking with the raider the player ought to assure him that no one's going to hurt him, and basically cave in to his demands. If their speech skill is high enough, they can convince him to leave without a fight, but if it isn't high enough they may need to pay him either 100 or 200 bottle caps, depending on what they say and when.

Violent method
Another solution is to begin talking with the crazed raider in a calming manner. If he says he needs to think about it, the player should walk in on him. He will attack them instead of Sinthia, allowing the player to kill him and save the prostitute.

Sneaky way
Again, like the option above, the player should talk to him in a calming manner. When the raider says he needs to think about it, the player should activate the sneak skill. If it's high enough, they'll be able to sneak behind him without him reacting. Shooting him will knock him unconscious. At first, Sinthia will think he's dead, but the game confirms he's not.

Rewards

 * 1000 or 400 XP.
 * A free night at the Crash House.
 * Sinthia's "services".