The party had a few days to get ready for their first official mission for the resistance, destroying a weapons cache for the gnolls. They hunted down and killed rust monster and George took it to an alchemist who made a powder out of it. With that and some alchemist fire they figured they would be able to destroy most if not all of the weapons they wouldn't be able to carry out.
Esme stopped by Wolpertinger Caves and showed them the posters that had gone up all around Meadowfen, calling all of them the Butchers of Meadowfen. She also told them to get in touch with Mésis, he probably knew where the weapons cache was that she'd heard rumors about.
The meeting with Mésis went well, he wanted a meeting with Kuato which the party couldn't guarantee, but assured him they would pass the message along. Not completely satisfied, he asked for them to steal a seal (a scorpion in the shape of an S) and the sealing wax from the tower where the cache was. He promised it wasn't for his own profit, but rather to mess with the gnolls who were becoming a serious problem for the thieves guild. The party agreed, but asked for access to the seal as well if they saw an opportunity.
On the way to the tower (north of Winnowing Reach) they came within sight of the main road that goes to the western towns. A prison wagon and roughly 20 gnolls was on the road. The party recognized Tam Loxwood and Buff Orpington in the wagon cage. They followed the wagon from a distance and came up with a plan. There were too many gnolls to take on, so Cyrus would sneak up to the wagon and give Tam a rock that Amichai had studied enough to cast Locate Object. Everyone was pretty sure they were going to the prison in Ashbarrow, and the Locate Object would let them be able to pinpoint where Tam was.
Cyrus stealthed up to the wagon without any trouble and gave Tam the rock. Buff overhead him and passed along his journal, which he didn't want the gnolls to find. It had all the information he'd collected over the years about the Lost Temple of Tyton. He'd planned on searching the Isle of Tyton, but the gnoll invasion interrupted this.
Almost forgot, while the party was watching the gnolls Amichai started glowing a dark purple that got brighter and brighter. It culminated in an explosion of light, much like what happened in chapter 02: Goodwill to Glenhaven when the remnants of the gate erupted in a last explosion of magic. Amichai was unhurt, in fact he felt even healthier and heartier than he had before.
A day later the party arrived at the tower. They waited until night and Adina sent her familiar up to the top of the tower to look for a way in. There were stairs going down, along with a Wyvern. The owl was able to explore several rooms, two of which had piles of weapons.
The party entered the tower through the second story windows. They made their way up and realized there had to be secret rooms throughout the tower. At the top Cyrus set the Wyvern free from the chains that kept it there and the party found a secret trap door. Following this they came into a study where they grabbed all the papers and a map of Humblewood. They also found the seal and wax that Mésis wanted.
Descending further the party entered a laboratory that had some poisons on a table. There was also a weird alchemical skunk and a wall with a lot of arms that almost killed two of the party members. Once that was dealt with, Cyrus unlocked a cabinet and they found the Bow of Reya that belongs to Dúne's mother, a Ring of Valor, and a Wand of Nystul's Magical Aura.
Exploring the tower a bit more they freed two folk that were the slave cooks for the gnolls. They let the party know there were only four gnolls now in the tower. The one in charge had left suddenly a week ago. They also said the gnolls became rather lazy when the head gnoll was gone.
This turned out to be very true, all the gnolls were sleeping so the party took all their weapons and attacked. One of the gnolls was able to summon hyenas, which was a bit of a surprise, but the party handled it quite well killing all the gnolls and not even saving one for questioning which wouldn't have mattered anyway because no one speaks gnoll. So there's that anyway.
With that, the party finished their mission. They took as many weapons as they could carry and destroyed the rest.