How is metaphysics explored in The Crying of Lot 49?

A mystery novel where the protagonist delves into deep philosophical questions while trying to solve the mystery is known as a "metaphysical detective story." The quintessential postmodern novella The Crying of Lot 49 by Thomas Pynchon is such a work. This relatively short, brilliant, and bizarre book is so dense and convoluted as to be almost impenetrable, while simultaneously offering a witty and multilayered picture of Cold War paranoia. Thus, as the protagonist Oedipa Maas seeks to unravel the mystery behind the Tristero, a secret organization that may or may not exist, we as readers are just as puzzled and upended as she is after unexpectedly being named executer of an enigmatic estate.
Oedipa's quest to resolve the estate's matters loosely forms the structure of the novella, and as she pursues dead end after unsatisfying and weird dead end, her strange journey transforms into a metaphysical rumination on the nature of reality. Scattered throughout the novella are metaphysical references such as the National Automobile Dealers Association sign swinging in the wind, N.A.D.A. meaning literally "nothing" in Spanish. Fittingly, at least some of these references turn out to be red herrings. As with the great Cold War conspiracies, each odd happening opens a rabbit hole where little resolves but more questions arise. Events that seem meaningful turn out to be coincidental. Or are they?
At the end of the novella, Oedipa and the reader are waiting with great anticipation to see who shows up at an auction, and the journey ends abruptly. The reader is left with many questions and the urge to re-read the novella to find more clues. This labyrinthine attraction speaks to our times and is probably the main reason why The Crying of Lot 49 is still so popular 50 years after its first publication.