The 'Olympus Has Fallen' novel is likely about a story where the White House (referred to as Olympus in a symbolic way) is under some sort of threat or attack. It probably involves characters trying to defend it against various antagonists. However, without reading it specifically, it's hard to give a more detailed account.
In the 'Olympus Has Fallen' novel, it may focus on a high - stakes scenario. There could be a group of terrorists or enemies who manage to infiltrate the highly - secured White House. The plot might then revolve around the heroic efforts of the main characters, perhaps some special agents or military personnel, to fight back, rescue hostages if there are any, and restore order and security to this most important of American buildings.
Well, the 'Olympus Has Fallen' novel might explore the concept of a nation in crisis as its very heart, the White House, is in jeopardy. It could detail the chaos that ensues when the unthinkable happens. There may be political intrigue as well, with different characters having their own motives and agendas. It might also show how the nation responds on a larger scale to such an attack on its most iconic building, and how the characters' personal stories are intertwined with the overall struggle to save Olympus, which represents not just a building but the nation's leadership and stability.