The Old Man in the Corner, by Baroness Orczy
I'd vaguely heard of the Old Man in the Corner as one of the early detective classics, but I hadn't realized that the stories were by Baroness Orczy! So then of course I had to read some, which is easy now that you can download that sort of thing from Google Books or Amazon Kindle for free. These stories, as with so many others, were originally published in magazines, so the repetition wasn't quite as obvious; it just re-established the characters in the readers' minds.
In each story, the young and modern Lady Journalist meets up with the Old Man as she's trying to eat her lunch in a restaurant. He then lectures her on a current criminal mystery, and solves the whole thing while he sits there, fidgeting with a bit of string in which he ties complicated knots as he talks. He also consumes milk and cheesecake. (Oog.) The lecture always falls into three parts: he summarizes the case and produces a photo or two of the people involved, he contradicts the young lady's interpretation and analyzes everything, and then finally he comes up with a miraculous answer while she stutters in shock.
Although the mysteries themselves are
interesting enough, the framework is pretty hopeless for a modern reader. The Old Man is irritating and the action is distanced by the frame. The Lady Journalist never gets to say anything; she's just a spectator. If you're interested in the history of mystery stories, you should read it; otherwise; skip it without a qualm.