Oedipa goes back once again to The Scope, where, as usual, she finds Mike Fallopian. She tells him of her progress in unwrapping the mystery. Mike asks if she has ever considered the possibility that the whole idea of the Tristero is just one huge gag invented by Pierce as a means of fooling her. While the thought has crossed her mind in the past, Oedipa refuses to acknowledge it as a possibility. She starts to get angry and leaves the bar.
One day, Genghis Cohen calls her. He has a stamp from a U.S. mail bag with the words "We Await Silent Tristero's Empire" written in the corner. Oedipa realizes that this is the elongated version of the W.A.S.T.E. acronym. The letter on which the stamp was found came from Zapf's Used Bookstore in San Narciso. Oedipa goes back to San Narciso and frantically looks through all of Pierce's assets. As she has come to suspect, Pierce owned Zapf's Used Bookstore, as well as the government surplus store next door. In fact, Pierce also owned the Tank Theater, where she had seen Driblette in the production of The Courier's Tragedy. Oedipa slowly realizes that every single route that has led her to the Tristero can also be traced to the Pierce Inverarity estate. She recalls that even Blobb's Peregrinations, which recounted the Tristero story, was purchased at Zapf's. Emory Bortz, she sees further, is a professor at San Narciso College, a school heavily endowed by Pierce. Oedipa suddenly begins to suspect that perhaps Pierce has bought every single person whom Oedipa has met and asked them to help orchestrate the joke.
No longer sure about anything in her life, Oedipa spends the next few weeks alone, obsessed, and very troubled. She endures all sorts of medical problems. Meanwhile, Genghis comes up with new information each day. He finds an 1865 article discussing the decline of the Tristero from 1800-1850 due to internal fighting. The Tristero followers, he finds, most likely came to America in 1849 or 1850 and immediately moved to the open west, where they began stamp production. Oedipa, however, questions the legitimacy of the article. Her odd dreams and toothaches are getting worse on a daily basis.
One day, Genghis tells Oedipa that Pierce's stamps are being auctioned off as Lot 49 by a local dealer. Genghis tells her that a man named C. Morris Schrift is acting as the agent for a special new "book bidder" who will not be at the auction. Her interest piqued, Oedipa goes to the auction. When she arrives she is told by Genghis that the mysterious bidder represented by Schrift is actually at the auction. Oedipa suddenly begins to realize that the man who bids on Pierce's stamps may be the sole key explaining the whole mystery. Anxious for the bidding to begin, Genghis explains that at auctions, the person who handles all the bidding and calls out numbers is called the "crier." Oedipa sits down nervously in a chair, anxious to see who the mysterious bidder is as she awaits the crying of Lot 49.
Without a doubt, the most striking thing about this section is its ending, which also ends the novel. We do not find out who the mysterious bidder is; the novel ends before the auction even begins. In one sense, this is very frustrating. It is entirely unsatisfying for a detective story to end without revealing whodunit. But at the same time, Pynchon may be indicating that it does not matter who the mysterious bidder is. The abrupt ending is a way of indicating that the important parts of the novel, such as the problems with Oedipa's life and her seclusion, have been fully presented. The whole Tristero plot, in this case, seems secondary. What we do know at the end of the novel is that Oedipa has become detached from the mystery and that she has become separated from her friends and loved ones due to communication failures and drugs. The novel has done what it set out to do.
Let us briefly speculate on some possible endings. The mysterious bidder, of course, could be Pierce himself. That would mean that the whole Tristero plot has been one long and cruel joke on Oedipa with all sorts of actors and a fictionalized world. If Oedipa has been merely the subject of a prank, then many of the plot elements of the novel will have been altogether meaningless. Oedipa will have been through a brutal and alienating psychological trip only to find out that she has lost her friends and family for a vicious gag. Of course, perhaps the mysterious bidder is someone else whom we have not yet met. The mystery then would only deepen, likely into infinity, entangling Oedipa as it expanded.