A shift in power dynamic is evidenced in this novel by the fact that Amy Dunne sets about to take over and ruin her husband Nick Dunne's life in the aftermath of discovering that he had been unfaithful to her.

When Amy "disappears," she frames Nick by leaving behind a series of clues that are intended to lead the police to the conclusion that she has met with foul play at the hands of her husband. Her plan works, and Nick is immediately the prime suspect. Her plan to punish him for his infidelity involves having him found guilty of murder and sentenced to death—at which point she will end her life.

Prior to Nick's infidelity, the power dynamic in their relationship seems to have been relatively normal: she was responsible for her decisions and he was responsible for his. In the aftermath of Amy's master plan, however, Nick is no longer in control of his world. This is taken to the next level some time after Amy's "miraculous" return, when she announces herself to be pregnant with Nick's child, thanks to sperm that Nick had frozen earlier in their marriage. The realization that he cannot leave his child alone with the monster that he has married completes the shift in power dynamic, as he is now stuck in this toxic marriage indefinitely.