Maxwell Lord has taken control of Superman, and has driven him to delusional destraction, believing he is fighting some of his greatest foes when in reality it is all Maxwell Lord's doing. Wonder Woman follows Superman to confront Lord, but she is presented with something much worse; the full force of a mind-warped Superman who believes her to be a threat.
An epic battle ensues, with Wonder Woman having to slice Superman's throat with her tiara to slow him down.
Max Lord gives Wonder Woman an ultimatum; he'll relinquish control this time, but can and will do it time and time again, or, to stop it indefinitely, kill him.
Wonder Woman then proceeds to do just that, breaking Lord's neck.
This action leads on to the whole world seeing Wonder Woman in an entirely different light, and brings about the end of the Justice League, until after Infinite Crisis.