I hadn't read an Agatha Christie for about 30 years until I picked this up on spec at a station bookstall and I was delighted at how much I enjoyed it.
The Secret of Chimneys is an early (1925) Christie and is much more of a light-hearted romp than her more famous books. The plot is too complex to precis here (besides, I don't want to spoil your fun) although it involves, inter alia, Balkan revolutionaries, daring adventurers, stolen letters, missing diamonds, and, of course, a brace of mysterious murders.
The characters are very Wodehousian - amiable young men about town, flirtatious flappers, vague and woolly-minded peers - although, as usual, not everybody is what they seem and I doubt if even the most astute spotter of red herrings will work out who is really who, let alone whodunnit, before the loose ends are all adroitly tied up in the last couple of chapters.
There is not as much detection as in, say, a Poirot (indeed, her characters make a number of mock disparaging references to detective fiction throughout) and some of the 1920s attitudes may set a few teeth on edge today - foreigners are blithely referred to as dagoes, the Jewish characters have big noses, etc - but that shouldn't detract from an immensely enjoyable caper that brims with period charm.