The girls and Havelock have been wandering around without much goal for a while, now. They'll stop at this town or that city and engage in a bit of trade, some healing, whatever they need to do in order to make sure that this place isn't going to burn two of the three of them at the stake, or make life harder on the third one.
Medicine Lake is, unsurprisingly, a lake with a small trapping town near it. Herds of wild gillydeer and fur flounder bask under and around it, and it's a popular destination for people more likely to trust water than water Masters and Aligned. The water itself, perhaps due to the plants that grow under it, perhaps just as a quirk brought on by the Solution itself, is good for mild pain relief and antiseptic properties.
Whenever they're in the area TJ likes to stop there in order to pick up a load of it for her own personal use as well as to trade and sell if needed. Clarice has contacts amongst the trappers and fishers to trade grains for meats, and while she does that TJ offers her services for whatever ills the people of Medicine Lake have to admit that the water of their home just isn't up to.
This time she dragged Havelock with her, thanks to an outbreak of a fairly nasty illness hitting the local human population like an angry gator.
It's while in the house set up as temporary sick-ward that she says, "So. About that letter Clarice got yesterday..."