Sunday, August 18, 2013. After remembering the violence in the underpass, Rachel has some kind of breakthrough. She is able to reflect on memories she’s had while drunk—memories Tom always told her weren’t true—and reevaluate them. Though Rachel is exhilarated and vindicated by the realization that Tom has been gaslighting her for years, she is unsure of what to do with this realization. She calls Tom’s house but then hangs up. She calls Riley’s office and hangs up again. Rachel is sure that no one will believe her. She hurries to the train and, as she stands on the platform waiting, continues to go over the memory of that fateful Saturday night. She has yet another revelation just before the train pulls in: the woman in the blue dress she saw wasn’t Anna, but Megan.
As Rachel experiences a breakthrough, she finds herself feeling free and vindicated. She can at last perceive and confront the years of abuse and gaslighting she suffered at Tom’s hands—and as more and more memories flood back to her, she begins to accept the terrible truth that Tom, who portrayed himself as the victim all along, may in fact be Megan’s murderer.