The Crying of Lot 49, published in 1966, is Thomas Pynchon's second novel. The shortest of Pynchon's novels and often considered his most accessible, the book is about a woman, Oedipa Maas, possibly unearthing the centuries old conflict between two mail distribution companies, Thurn und Taxis and the Trystero (or Tristero). The former actually existed, and was the first firm to distribute postal mail; the latter is Pynchon's invention.
https://cl49.pynchonwiki.com/wiki/index.php?title=The_Crying_of_Lot_49