The big arrow pointing from left-to-right is the main plot, the through-action of the detective story and that's all very straightforward (as detective stories go). It serves as the 12-chapter, three-act framework onto which I'm hanging all my literary experiments. This plot provides the primary forward motion of the novel, the story question ("who killed George Pullman?") and the overall dramatic arc. There is also a fairly normal sort of subplot involving the emotional life of the detective that will be resolved in a fairly normal sort of manner. All of that's represented by the black arrow in the diagram.
You've noticed by now that there are also 10 colored dots through which the plot arrow passes on its way from page Start to page Finish. These represent individual characters in the novel. Every one of the characters has his/her own story that is separate from the mystery plot. But these characters' stories are not subplots, because they do not develop over time and are not resolved within the confines of this novel. They are more like lengthy character sketches through which the detective story passes while the detective investigates the crime. Since they are, plotwise, fairly static, I have decided to call them Nonplots, which sounds a bit derogatory so I'm open to a better name.
The inspiration for this Nonplot substructure of the book comes from, first of all, Agatha Christie. Last year I was reading her Poirot mystery Halloween Party and I was struck by the long digression Christie took in the middle of the novel to talk about landscaping and gardening. It's some of Christie's most beautiful writing and had nothing really to do with the story going on around it. I thought it would be cool to do something digressive like this in a detective story. I also have been inspired by Louis de Bernieres' Birds Without Wings, which is a long historical novel containing a bunch of character arcs that intersect but don't necessarily tie together in a direct way. Finally there's the work of Virginia Woolf and Samuel Beckett and James Joyce, who wrote brilliant stream of consciousness novels where the internal action is very dramatic and compelling while the external action is fairly simple.
My Nonplots, then, are explorations of the characters in my novel, places where the plot slows down and the characters are expanded through internal monologues and suchlike stuff. The drama of these sections comes about through the use of conflict. The book is charactered with a bunch of couples of different ages in different stages of couplehood, and each Nonplot is a rumination by one half of the couple about the relationship. So you get both halves of the couples eventually (in my diagram A and F, for example, could be one couple while B and J are another), and each member of the couple will have their own point of view regarding their marriage/relationship. So I'm examining pairbonding, but not really telling full stories for each couple.
What this means is that the Nonplots overlap and connect and form little miniature arcs in the narrative, but there is no resolution, no thing that happens with these characters. Of course things happen to some of the characters related to the primary murder mystery, and there are of course connections between those events and the internal monologues in the Nonplots, but the connections for most of the characters are pretty tenuous. In a lot of ways, I have just realized, the book is like eating with a bunch of strangers in a resort dining room, where you chat at breakfast and maybe again at dinner with the charming couple from Nantucket and you never do learn how things will work out for their nephew in medical school or whatever. But deeper and more immediate than that. Maybe it's more like walking through the National Gallery and looking long at each painting and then moving on. Not sure, frankly, nor am I entirely certain how this structure will play out when the book is finished. I'm excited about it, though. It could be really cool if it works. And none of this stuff I've talked about today is the "philosophical" part of the philosophical detective story. That's an extra layer of ubercoolness atop all of the aforementioned coolness.

