You might think that once you finally hit Act 3 of Baldur's Gate 3 and are presented with civilization you could take a breath and just relax for a bit, but you'd be wrong. The first thing you'll see when you walk into the very first town in Act 3 is an argument between three people, and it leads to an extremely interesting side quest.
Find The Suspicious Toys And Disarm Them
First off, you'll need to get yourself involved in the conversation and attempt to read the thoughts of the man who refuses to house any refugees in his house. By doing so you'll discover that he's extremely worried about the refugees finding something in his basement.
You can try and persuade him to let them into his house, but you will have to face down the anger of the mercenary group that is being paid to keep them out, but with how your overall stats should look right now you should have a pretty easy time doing that.
Go into the house and the room to the left as you enter. That room has a hatch in the floor that you can access once you move a few items around, and it'll take you to the basement. Be very wary here, however, as there are traps dotted EVERYWHERE. If your perception isn't great then you might want to switch to a different character so that you can see and disarm them, but once you do make your way over to the main area of the basement where you'll find a letter that indicates there's something wrong with the stuffed toys that the owner of the house has donated to a local shelter for refugees.
Travel to the barn to the right of the house and talk your way into it to find the stuffed toys and investigate them. You'll be presented with a check to see if you can disarm them because, surprise, they've got explosives in them. You're now tasked with going after the person who donated them, but you won't be able to get to him until you get to Baldur's Gate itself.
Finding Arfur
Depending on the way you handled the refugees earlier, Arfur will either be in his house or in the performance room of Sharess' Caress. You have to pass an intimidation check in order to get information from him and if you do he'll tell you about deliveries he's been receiving from Felogyr's Fireworks. He'll also give you his Admission Pass so that you can get past Wyrm's Rock Fortress.
Once you've found him and got this information you need to make your way into Basilisk Gate and find Felogyr's Fireworks. You'll find the establishment south of Sorcerous Sundries. Inside you'll discover Avery Sonshal, an employee, and somebody else who has the Absolutist Tadpole inside of his head. Going upstairs will uncover an area where guards simply won't let you pass, and it's in here that you'll discover the secret of a group of Banites, who are stuffing explosives inside children's toys.
You'll have to fight them extremely carefully since they're surrounded by explosives. The briefest and smallest spark will set them off, and the entire store will go hostile against you. Defeat them all and you'll complete the quest.