After traveling to House Frey's fortress The Twins for a feast to celebrate their victory at Riverrun, Jaime returns to King's Landing. Upon arrival, he is horrified to discover that the Great Sept of Baelor has been destroyed in a wildfire explosion, with the majority of House Tyrell and the entire Faith Militant killed in the attack. He returns to the Red Keep in time to witness Cersei being crowned as Queen of the Seven Kingdoms, immediately realizing that Cersei wiped out every high-ranking rival in the explosion in order to acquire her new power.