[written Dec 1, 2015 catching up.]
Uncommon Danger is in the 4-volume Eric Ambler omnibus, but the copy I read I found in my parent's guest bedroom bookshelf, a really old paperback with a breaking spine and flaking corners. I read it anyways. It was great, though I preferred the setup (with the down and out journalist on his last dime crossing a frontier with unknown contraband) then the conclusion. Still, great stuff.