The Puzzle of Blackstone Lodge by Martin Edwards
The Puzzle of Blackstone Lodge is set in Yorkshire in the 1930's. Nell Fagan is somewhat desperately trying to find a great story to get back in the good graces of a good London newspaper. She's on the trail of something possibly big in the small town of Blackstone Fell, looking into historic and modern disappearances as well as the local sanatorium. When she realizes the extent of her possible case, she decides to consult Rachel Savernake, our "amateur" sleuth. She is not 100% honest about what's going on however and Rachel dismisses her. Nell returns to Yorkshire to continue her investigation alone and with difficulty. Meanwhile, Rachel enlists some associates to look into the matters, too.
It's a good story with a lot going on. The disappearances are a locked room mystery, but more of a sidelight to the main plot. We've got seances, dangerous caves, and a spooky tower, and Nell was right to be suspicious of the...