The continuing contribution of Eric Ambler.

Ad for the 1943 film of
Eric Ambler's Background to Danger

John Gray pens an appreciation in the BBC Magazine of the spy novels of Eric Ambler (e.g., Journey into Fear, The Mask of Dimitrios):

The protagonists of Ambler's novels aren't the hearty public school patriots who stride through the pages of John Buchan.
. . . Ambler's novels are unsettling in a number of ways. 

(thanks to the Law & Humanities blog)