A. Lee Martinez' Too Many Curses takes place entirely within a castle. The castle is owned by a wizard, who has filled it with various weapons, items, tomes, creatures, and the many, many people he's cursed over the years. Also within the castle is a kobold named Nessy, responsible for keeping things neat and orderly. She takes this job seriously and does it well, despite receiving no praise, and being certain the wizard will someday seize upon an excuse to kill her. Except it's the wizard who winds up dead, at which point things begin to go very wrong in the castle, and Nessy has to try and hold everything together, with the assistance of some of the cursed inhabitants.
Even though the lives of everyone in the castle are at risk, Martinez maintains a light tone. It's accomplished primarily through Nessy, who is a very practical, sensible creature. She doesn't worry about problems that haven't occurred yet or that are beyond her control, preferring to focus on matters at hand she can deal with. She doesn't give in to fear readily, which keeps her and those around her a bit calmer. As things don't devolve into complete panic, the situation doesn't seem hopelessly dire. She isn't a wizard, but she knows the castle well, and can use that to her advantage. She's cautious, though, and this makes her a bit slow to accept that the pecking order has shifted in the castle, and even once she accepts it, it's a bit longer before we see an adjustment in how she carries herself. had she embraced the change sooner, things might have gone more smoothly.
There's also quite a bit of dry humor, usually in the narration, and even a riff on a Bugs Bunny/Tasmanian Devil gag I enjoyed. The cast of characters is suitably strange, since it consists of people cursed and entrapped by an evil wizard, and I think it helps the story that everyone involved accepts these sorts of things as part of the world. Not that most of them are happy about being cursed, but they recognize they live in a world with evil wizards, and sometimes those evil wizards curse you, and then you have to hope the wizard dies and the curse wears off, or that you're uncursed some other way. They're probably much as they were before they were cursed, but they've adjusted to the limitations of what they've become. It helps create a sense of their world, more than if we'd been introduced to the place through some recently cursed character who spends their time shocked that such a thing could happen.