The story is highly complicated and has all the tropes you expect from a Golden Age mystery, its set in a dark country house and includes a cast of toffs, flappers, a bumbling (but ultimately efficient) police detective, perky keen amateurs and plenty of red herrings and puzzles. There is even a map!
The book is well written and an enjoyable read, it just about manages to err on the right side of parody though at times a close run thing. A superb send-up and celebration of a genre.