It's easy to confuse this one with They Came to Baghdad, seeing as they both begin with a grey eminence in the secret service discussing the recent developments with a portly colleague, and the eminent intelligence officer recruiting a young woman who's got no experience, just a lot of chutzpah.
Luckily, they diverge a bit in the execution of the main plot thereafter, and it's to this novel's advantage. There's fewer coincidences and amazing happenstances. While I'd never call the plot here plausible, at least the events in it make some kind of internal sense. While Victoria in the previous novel always made the exact right choices, Hilary is more a victim of circumstances. It is in fact not she who manages to reveal the whole megalomaniacal plot in the end.
Still, there's quite a lot of fun to be had on the way for the reader before reaching the end. The love story is again quite predictable - another resemblance of They Came to Baghdad - but we don't have to assume that an incredibly effective organization is foiled by a young lady stumbling into their clutches.
I'd rate this a 62 of 100. It's simply one of Christie's better thrillers.
A literal translation of the British title this time. The number of editions is pretty much what you'd expect from this title, one of Christie's thrillers and therefore a lesser known title.
The first cover shows the Arabic settlement which is the "unknown destination" of the title. As I've revealed by now, I'm not overly fond of angular drawings, but otherwise I think this is pretty nice. The way the settlement is perched on the cliff's edge looks suitably evocative.
The Zebra cover from 1958 is fairly similar to what we've seen for many other Christie titles. The difference is that this time the drawing style fits much better with the contents of the novel, since this is a thriller. There's a lot of action in the picture with the plane blowing up and the man running in the foreground. Some inspiration taken from a certain Hitchcock movie, perhaps?
The Delfinserien cover from 1980 you'll recognise as the Fontana cover. This is one of my favourites with the surreal view over the desert sand looking very evocative.
Finally, we also have two covers featuring planes by Leslie Quagraine. The earlier one is from the hardcover edition, while the later one belongs to the paperback edition. The hardcover variant looks more cartoony but still suggestive enough of the contents. The second is better, though perhaps a bit too dark in its colouring. We get the whole plane pictured in an angle that looks as if it's going to crash at any time. Some good stuff here among these covers, to be honest!
(By the way, isn't the plane on the British cover way up above quite anachronistic? It looks like an airplane from the 20s or 30s to me. Though maybe they were still in service in the desert.)