Interesting spy thriller from 1939. I've been on a bit of a kick reading spy novels from different historical periods (see also John Buchan's 19-teens-era novels Greenmantle and The Thirty-Nine Steps) and I'm finding a tremendous, completely unexpected benefit: I learn more history from reading this sub-genre than from reading history itself!
Journey Into Fear is set in pre-WWII Turkey, and it gives a reader context for a region of the world rarely talked about in standard Western histories of this era. Here you'll learn about the geopolitical dance between Turkey and Germany leading up to WWII, and you get a good feel for the tension in the air in the late 1930s throughout Europe. People knew that some kind of conflict--possibly a major one--was going to happen, but nobody knew when, where, who would be fighting, or who would be allied with who. It's all quite strikingly similar to today's era, with our proxy wars and shifting alliances, as a new post-American hegemony power structure takes shape.
This ain't Hemingway--it's good but not great literature. And the pacing is stately: readers accustomed to the formulaic pacing of Dumas (or, say, a modern reader used to Dan Brown) might even consider Journey Into Fear slow. But it also has some interesting proto-modern elements: the protagonist, for example, is sort of a dithering amateur, he's an engineer involved in developing naval guns, and he has no context (nor stomach, frankly) for spy work like murder and political intrigue. This isn't your suave James Bond: this guy is actually frightened and self-doubting as he tries his best to evade trained killers. Choosing an "average" protagonist like this is unusual and it adds (a little) to the tension.
I've now read two Eric Ambler books (I'll be writing up A Coffin for Dimitrios next, a better novel in my view), and candidly, they are both 3-ish (out of 5) star books. That's enough of a sample for me of this author.