Almost everything that happened in the book was just really convenient or highly unrealistic. Katherine just happened to have a license for carrying a gun near the end of the book? Her teenaged children aren't even concerned about her when they hear about the cruise ship bombing, and instead ask her to have fun in Italy and not to bother coming home so soon? Her sixteen-year-old son giving her an enthusiastic hug when she does go home? Since when do teenaged boys hug their mothers so enthusiastically? That sounds more like something a younger child would do, and anyway, he wasn't worried about her either and that's why it's really not realistic the way Graham described that scene. You'd really have to read it to see what I mean.
One of the most unrealistic things of all, Katherine's best friend just happened to... Oh wait, that would be giving away spoilers. Actually, there are so many details about the book which bothered me, but I can't tell them all without giving away too many spoilers. So if you're interested in finding out how not to write a suspense novel, I suggest you read Majestic Descending for yourself. It's not really all that bad, despite all the clichés. You’d enjoy a good laugh, at the very least.