Please also bear in mind that this story is very controversial and many fans think it's terrible. I'm trying to firstly stay focused on the Empire and secondly keep the cast of characters small, so that someone who has only played Vermintide might be able to follow it. I know some things are more complicated than what I say here.
To people who know the setting very well: this version is intentionally shortened and simplified. A complete summary of the End Times would be extremely long, and it would take me an hour or two to write tomorrow, but I'll try to give a short version.