The main characters are the cast of Worth the Candle playing a game after that story's end.
Verity ran away from the pressures of her music career in large part because being one of The Chosen of the god Xuphin put great expectations on her. In the first dungeon, she found an entad (shaped like a musical instrument no less) adds additional fingers to the user's hands, along with the muscle memory to use them. Since Xuphin is the god of Increase, this is a sign that this Party is right where they always intended her to be.
Isra is one of the druids manufactured by Tarbin.
Isra's father and mother were a couple recruited for the program, and the entads they brought to Inter were originally loaned to them by the Tarbin government. They had second thoughts for whatever reason, and fled to Inter. They chose Pucklechurch because it was out of the way and it was unlikely anyone from Tarbin would ever find them, and it was mostly coincidence that it was far enough away from people that someone could become a druid. When Isra's mother died, her father was uniquely positioned to care for her on his own because the couple had already been preparing for it and had been given entads specifically suited to the task of raising a child in isolation.