Crisis On Infinite Earths

The very start of the series is reprised as it is revealed a single universe has now been created, rather than a Multiverse. Several Earth-Two heroes, however, appear to have awakened on Earth-One and, when they attempt to return find that it no longer exists. The heroes reconvene and work out that things have changed and that Earth-Two never existed in this universe but all the heroes of all the Earths who were at the dawn of time still remember their original Earths. As they struggle to come to terms with this, the Anti-Monitor appears and drags the Earth into the anti-matter universe.