Black Cabinet

"Black Cabinet" by Patricia Wentworth is the tale of a young heiress who uncovers dark secrets of her inheritance, details of which are locked up in a large piece of furniture. 

A brutal gang want to silence her (and get their hands on her inheritance of course)...

A fast moving adventure with continuous peril. An enjoyable read though the heroine was a bit wearisome at times as she makes a few decisions which seem a bit odd, though it helps to pad the story out a bit. 

The energy of the story helps pull you through.