You find the corpse of a young woman with an odd veil, which triggers a quest to investigate Riverside Manor. If you go there, you find a large mansion and guest house that was the home of Shannon Rivers. The name might be familiar to anyone who played Fallout 4 - she was the voice actor who played the Mistress of Mystery in the radio plays for decades, the one who was dumped by Hubris Comics for the upcoming Silver Shroud film that had the two characters working together in favour of a pretty young woman who didn't fit the character at all. In her home, you find that her husband (working with Kent Connolly, the avid Silver Shroud fan from FO4) had a precise replica of the Mistress of Mytery's training facility built under their house and hired a variety of trainers for her - he knew how worried she was about playing the character on screen so he gave her the chance to train to be able to do it for real in order to help her gain the necessary confidence. A lovely story...which doesn't stay lovely. This is the Fallout world, not the Disney world.
After the war, Shannon Rivers used those real combat skills she'd learned when some raiders attacked. After that, she decided to take in orphaned girls and only girls. Boys were turned away by force (she presumably killed those who wouldn't leave and presumably some starving desperate children wouldn't leave), as were adults (presumably - the only adults mentioned were old men and nothing was said about what she did to them). The girls were trained the same way, forming an organisation - The Order of Mysteries.
But it gets even grimmer than that. Shannon and her husband had a daughter, Olivia. A big turning point in Olivia's life was when she watched one of her childhood friends being turned away to fend for himself (and probably die) in the post-apocalypse world because he was the "wrong" sex. Olivia went through the Order of Mystery training, but was skipped for any important role in the organisation. Correctly so because she was rather lacking in any sort of leadership ability and not a very nice person anyway, but it festered and took her further along the path she followed. All the killing she did certainly didn't help, especially since it didn't matter how many raiders she killed - more kept coming. Nor did it help that her mother kept the Order secret, not openly helping anyone, because the Mistress of Mystery was a secret identity in the comics. She came to consider her mother to be deluded, ludicrously trying to apply a pre-war comic book to post-war reality. Then she met that childhood friend her mother had dismissed to fend for himself or die because he was the "wrong" sex. He'd survived by joining a band of raiders. Olivia devised a scheme to become a raider leader, planning to unite all the local raiders under her command. That childhood friend was her essential liason with the most powerful local raider leader and through him she sold out the Order, providing that raider leader with information about Order movements that enabled him to ambush and kill Order members one by one. In exchange, she'd get a high position in that raider gang. Finally, she killed her mother and thus ended the Order...and her childhood friend then killed her because she was no longer useful to the raider gang and was now a threat. The raider leader wasn't an idiot - he knew she'd betray him sooner or later, killing him to take his place as part of her plan to become grand dictator of all raiders. So he had someone she trusted kill her in exchange for favour. You find the final part of the story on the corpses of Olivia and Shannon Rivers.
Now that's a Fallout story - grim and ugly and all round nasty.