The main characters in '10 days in a madhouse novel' are likely to be a diverse group. Firstly, there would be the patients. Some might be long - term residents, while others could be newly admitted. Each patient may have their own story, like a young woman who was wrongly committed and is fighting to prove her sanity. Then, there are the staff members. There could be a cold and calculating doctor who believes in strict discipline, and a warm - hearted attendant who actually cares about the patients. There may also be other supporting characters like visitors or family members who come to the madhouse, adding more layers to the story.
The main theme is likely to be the experience within the madhouse. It could explore the conditions, the people there, and perhaps the treatment of the patients.
One key element could be the isolation. Being at the end of the earth implies it was far from civilization. Another might be the people involved, both the patients and the caretakers.
I'm not entirely sure which specific 'madhouse at the end of the earth' true story you are referring to. It could be about an asylum or some sort of institution in a very remote location. There might be various accounts of such places in history, perhaps related to the isolation and the strange things that happened there.