First published in 1939 this remains a remarkably fresh detective novel. Plus ça change - here we have not just murderers (who are always with us) but drug dealers, people traffickers, shady nightclub owners, assassins and, perhaps best of all, a dodgy bank registered in Monaco so that it does not have to publish anything or pay taxes.
The third-person narrative casts a writer of detective novels as its lead character who sets out in search of the history of a recently deceased criminal only to discover him, eventually, alive. The fiction writer, described as a prig by one of the underworld characters with whom he gets involved, is led on - as we all are - by fascination with the Other: those on the other side who make their living, and their lives, by breaking laws or moral taboos rather than enforcing them. Ambler explores this fascination at some length by setting up a working relationship between the writer Latimer and the crook Mr Peters. Just sometimes one feels that Ambler has Latimer protest too much, just in case the reader is tempted to conclude that he has been seduced by the other side - and this is perhaps the only aspect of the novel which feels a little dated. A modern writer might have fewer moral scruples or worry less about moral ambiguity.
It's a very good read. Ambler makes quite generous assumptions about his readers' general knowledge and willingness to add to it. It is quite a pleasant change to read someone who does not assume you are ignorant or determined to remain so.