Characters · 1946
Convenient, the door being open when you didn't have a key, eh?
— Eddie Mars · The Big Sleep

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The speaker remarks, with a sceptical 'eh?', that it was handy for the door to be open when the person addressed had no key. The words insinuate that the convenience is suspicious and invite an explanation, though they stop short of saying outright what is suspected.
Context reviewed