This is an odd book. It does remind me a lot of Passenger to Frankfurt, but, at least so far, it isn't nearly as awful as that one. Although it was really the ending that blew up that book, so there is still time.
Christie had a really bizarre obsession with the "elites" basically starting their own society to take over the world. Her late thrillers - They Came To Baghdad, Passenger to Frankfurt, and now this one, remind me a bit of Rand's Atlas Shrugged, although Christie definitely frames hers as cautionary tales, while Rand basically glorifies the idea of (her formulation) "the makers" abandoning "the looters" to death and starvation.
Destination Unknown doesn't have the charm of They Came to Baghdad, at least not so far. Hilary Craven (interesting name choice, there) lacks the manic pixie dream girl charm of Victoria Jones, being of a more serious, less effervescent, character.
At this point, though, Passenger to Frankfurt represents the execrable nadir of Christie novels for me, so anything that is, even slightly, less awful will be okay.