Pretty much, most of the Superstars are Killed Off For Real by Druids, and this goes on (with a tiny subplot of Santino and Vladimir being the only ones able to fend off the Druids) until Chavo calls out the Undertaker (because he thinks the Druids are his mooks), who comes to the ring and kills him. Then Edge comes out and tells him that the Druids were his mooks.

After a couple of battles, Undertaker kills Edge, who reveals that he's working for a new generation of The Four Horsemen. He then gets Kane, Santino, and Vladimir, and they all take out Goldust, another member. Soon, CM Punk gets recruited to be a new member after getting tortured by Arn Anderson. Then Santino kills Vladimir and Christian after he joins the Horsemen. (well, actually, he joins mid-fight by betraying Vladimir)

Then Kane gets killed by Santino and Undertaker gets pissed and beats him senseless. Then Arn declares his takeover of WWE and has an Elimination Chamber match which kills about five Superstars and has Randy Orton be the winner. Then Undertaker comes and kills Orton, but he is injured and is taken to the hospital.

Arn declares victory, but John Cena and HHH come in and tell him that they challenge him to a 2 on 4 match at Wrestlemania. After Cena and HHH take out Santino and Punk, but then Brock Lesner comes and kills them. Then Undertaker comes and takes him out, then calls out Arn to fight him. In the end, he chooses whether Arn is killed or arrested. 

And that's pretty much it.