Chapter 2-1
Lake
Look around the house for a few items. There is also an 'Anonymous Letter' here for you to read. Use the typewriter if you need to, then head outside.
Walk over to the dock, and you should find your boat still there. Jump into the boat, and head in the opposite direction of the dock. You should see blue flames in the distance, so head for that. Go inside the cave to find another Merchant.
Cave
Before you start shopping, check around the shop for a few barrels to break. Behind the barrels on the left side, you'll find a crate that you need to push. Head around the shop to find more barrels and a ladder. Grab all the items, then head up the ladder. There are two more crates to push here, so move them out of the way and you should find three barrels with items inside. You should find a Green Gem up here, which you can combine with the Elegant Mask, so make sure you do that. Grab any other items, and continue exploring the roof, you'll come across an opening that you can jump through. That hole will take you behind the merchant's counter, and you'll be able to pickup some additional ammo for the rifle. Head up the ladder, and get back to the front of the store. Time for more shopping...
Sell any treasures that you don't need. Remember to keep the Beerstein and the Elegant Mask (and the Green Gem if you have yet to combine it with the Elegant Mask). Grab yourself a few First Aid Sprays if you are running low on healing items, and upgrade your weapons for a little extra punch.
Get back in the boat when you are done. Head straight across the lake to reach the area where you first began this chapter (the house). Once you reach land, head left and go through the large double doors.