Readying themselves for the heist, the party gave themselves codenames based on flightless birds: Leila became "Rhea", Greta became "Dodo", Rasmus became "Cassowary", Ellenor became "Penguin", and Matthew the Ascended became "Kiwi". They purchased grappling hooks, ropes, and visited local herbalists before realizing health potions were too expensive. At Stable Reliable Steeds, Ellenor rented a getaway Draft Horse named Marx as well as a wagon big enough to hold the Stone; they painted "Cliffsunder Party Supplies" across the wagon to ensure no one would ever be suspicious of them. Leila magically communicated with Marx to earn his undying loyalty, which he would uphold provided that he was given ample food.
Ellenor re-applied disguises and donned the Bag of Holding as the party, dressed in finery, entered the museum to attend the gala. They were informed they could visit other exhibits, but were encouraged to head to the Gemstone Wing to see the grand unveiling. Ellenor and Leila did so promptly, with Greta hiding between Ellenor's legs in her ridiculously poofy dress. They masked this stealthy maneuver by chatting up the ostentatious noblewoman Helene Danforth, who was quick to gossip about the curator's incessant fidgeting with her clutch, as well as a rumour that she kept a human-sized doll in her office. Her ostentatious laughter provided enough distraction for Greta to sneak from the dress underneath a table, entering the Gemstone Wing without using her ticket.
Walking about without attracting much attention, Matthew clocked that in the small fossils exhibit, a couple of humans were discussing how a large jade stone behind a glass case would be "the perfect replacement", and that the wig of the woman was improperly placed. He also found that further on, there was a magical dagger and handaxe set behind another glass case, but when he asked the guard about it, was ushered to the Gemstone Wing.
As this happened, Rasmus chatted up Doctor Horthnar Stonecrusher, who revealed that the museum had undergone financial hardships and that the curator was supposedly quite stressed about the funds. He wondered where the money came from the purchase the Murkmire Stone, but was happy about the liveliness of the museum. During this conversation, Rasmus noticed that the display holding the allosaurus skeleton contained a controlled flow of necromantic energy, and had a switch system that could be used to make the dinosaur temporarily come to "life." He thanked the doctor and headed inside to the gala.
Inside the gala, it was obvious that everyone was waiting to talk to the son of the Port-Lord, Caelas Helefir. The noble was clearly of a status where he was allowed to carry a rapier at an otherwise unarmed event, and people questioned why he would come to an event aimed at scholars and donors. Leila decided to flaunt social conventions and interrupt his conversation with a military captain, and utterly failed to sway the lord. The entire room subtly turned against Leila, and Ellenor attempted to save face by saying Leila had fallen off a horse as a child, but ended up just socially ostracizing both of them. During this strange spectacle, Greta attempted to chat up the curator Alda Arkin by the Murkmire stone, and noticed that the two human bards hired to play for the gala appeared to be socioeconimcally out-of-place. Alda seemed nervous and busy, and didn't give much information to Greta, but clearly was fumbling with her clutch's lock the whole time.
Rasmus and Matthew convened, with Matthew explaining to Rasmus everything that he saw. Ellenor tried to pass Rasmus a note on the ground, but did a horrible job at doing so stealthily and attracted the attention of a guard, who picked up the crumpled paper. Acting quickly, Rasmus informed the guard of the possible "thieves" in the building, identifying the man and the woman with the poorly-concealed wig, and used the distraction to touch the paper and magically alter it's scipt to be a note on how hot Ellenor found Caelas Helefir to be. Embarrassed, the guard disregarded the note and went to the curator Alda to determine the best course of action.
Matthew heard from listening to other conversations that Caelas had an ostracized half-brother, Ulre Helefir, who had taken up a an adventurous life and shamed his family. The aarakocra decided to speak to Caelas as the gala wound down, and gambled by telling Caelas that he thought his brother was there, pointing to the couple that Rasmus had identified. Caelas questioned Matthew, who claimed to be a scholar and repeated one line about the Murkmire that he had read about in the library earlier that day. With a sneer, Caelas ran Matthew through with his rapier, and chaos ensued.
He didn't know it, but Matthew had got himself caught up in an unrelated family's troubles, and Caelas assumed that Matthew was working for his brother. He quickly had guards arrest the man and his companion, and Matthew was proven right as the thief turned out to be Ulre. The half-elf sneered and disappeared to the Ethereal Border Plane, leaving his female compatriot behind. Her noblewoman outfit was revealed to disguise a large scar across her left eye, and she and Matthew were both arrested. Greta was able to heal Matthew magically and recover her notebook, but did not want to become too closely associated with the bird. Matthew managed to slip out of his cuffs but kept them on for show, and they were escorted out of the gala. This was followed by an evacuation of all other patrons and most guards, who were commandeered by Caelas to find Ulre.
Rasmus and Greta used the commotion to hide in a storage closet as Leila and Ellenor decided to regroup outside. Waiting for things to calm down, the team outside decided that Leila would wait with their horse by the loading bay doors while Ellenor used a grappling hook to ascend into the museum. They donned their weapons and armor, then split ways. However, when Leila parked outside, she saw that the doors were already unlocked and heard the sound of two people ascending the stairs. She followed the noise, convincing Marx to stay put, and snuck up on a Crowfolk and a Dark Elf dressed in the gala's bard's clothes. They were busy lockpicking doors to the records room and main entrance, and with a crack of her Shillelagh staff, Leila knocked out the kenku thief.
Ellenor at this point had Mission-Impossibled her way down the skylight and into the nearby privies. She did not make a sound entering, but heard the sound of guards checking the doors to every bathroom. She cursed her luck and readied an attack on the guard who opened the door to her stall, but was unable to immediately silence him. Knowing that more guards would be on her tail, the half-elf bolted for the stairs, and suffered a cutting spear slash from the guard captain Maryam Bikram as she was chased to the main floor. She attempted an acrobatic maneuver from the stairs to the museum gift shop, but slipped and comically landed on her back. She was immediately surrounded by guards.
Meanwhile, Greta and Rasmus were stuck in the hidden storage closet, listening for the right moment to break out as Greta used the time to cast an Unseen Servant. On hearing Ellenor's commotion, they bolted, as Rasmus tried to check the Gemstone Wing's main entrance while Greta went to the side one. However, Rasmus found himself caught up in an encounter with another guard; thinking quickly, he maneuvered to the allosaurus skeleton, buying time from Greta's Unseen Servant who tripped the guard chasing him. With a quick flash of his thieves' tools, Rasmus "hacked" the console channeling the display's magic, causing a burst of necromantic energy. He ducked as the skeletal tail swung over him and crushed the guard; the undead dino was unleashed on the museum. It headed downstairs and immediately changed the priorities of the guards arresting Ellenor, who bolted through the door to escape.
The guards stumbled into the drow who was turning to attack Leila, and they disptached her and ran down to the loading bay. Leila let them pass and smacked Maryam, who was holding down Ellenor, with her Shiellelagh. This provided enough distraction for the half-elf to slip behind the captain and knock her out. They then ran into the records room and closed the door as a rampaging allosaurus crushed Maryam underneath it's massive foot. Upstairs, Greta tried to stealthily move between displays, but was seen by a guard. The unarmed halfling posed little threat to the spearman, and he stabbed her through the stomach as she magically charmed him to join in the fight against the allosaurus. The charmed guard agreed that the dino fight was the most important matter and ran off; as he left, Greta saw the two magical weapons that Matthew mentioned, shining on the other side of the display case.
Matthew had been taken by four guards, along with Ulre's wigless compatriot, to a carriage manned by two knights. He spoke to the guard arresting him, who identified as a follower of Umera. Learning that Umera held the same ideals and symbols of Torm, Matthew went through a small religious crisis before being thrown into the carriage. He attempted small talk but was continually silenced, and eventually resorted to claiming that he would shit an egg in Caelas' plush vehicle. The guards, unfamiliar with bird anatomy, were unsure if that was possible. Before Matthew could make too much of a stink, however, he realized that he was not taken to some prison, or royal hall, but to the seedy backstreets of Cliffsunder. He was lead down a foul-smelling hallway into a separate doorway from the scarred woman. Caelas led him in to a mostly-empty room, stained with blood pooled under a single decrepit chair, and started torturing Matthew for answers.
As Caelas was about to bring down the final hammer, however, the aarakocra's absurd logic managed to convince him of his honesty. Matthew revealed that he had been unchained the full time, and completely healed himself from the brink of death to fully healthy with a single Cure Wounds. This impressed Caelas enough to let him live, on the condition that Matthew now worked for him, and would help him hunt down Ulre. With little other choice, Matthew accepted, and officially left the party and the Golden Vault behind.