In movies, writers are generally allowed a couple of freebies. We're willing to suspend disbelief and not let something that seems patently absurd stand in the way of our enjoyment. Every good movie has to bend reality just a little. But that doesn't mean that the movies have to bend them in the same direction.

Here are two tropes common to political thrillers about presidential assassinations, White House destruction-ation-xplosions and such.

1. There's always a rogue Secret Service agent. This is the easy way to get around the "White House is an impenetrable fortress" stumbling block.

2. The bad guy always has nuclear destruction on his mind and must access the presidential football in order to launch nuclear weapons.

I don't like these tropes. They're kind of easy, and they're also terrifically implausible.

To point one: There has NEVER been a traitorous Secret Service agent. Ever. Surely there are other ways to get through the security gauntlet. I am not about to speculate about them in open session, thank you very much, but writers are supposed to be imaginative.

Two: There is no "nuclear button" anywhere near the President. Not on him. Not in "the football." Not in the President's Emergency Operations Center (PEOC).

The nuclear football has nothing to do with the actual launching of nuclear weapons. Nothing. The football, or the President's emergency satchel, contains a set of authentication codes that correspond to different scenarios, kind of like nuclear paperwork. The President authenticates himself over a secure line, the military aide cracks open the codes (they're in plastic, sealed thingies that the NSA makes and distributes), and then the President informs the Pentagon which option he prefers, and then uses the corresponding code to authenticate the choice. (A second person, either the Vice President, or Secretary of Defense, or others, must also authenticate the nuclear release option.) Then, and only then, are emergency action messages bearing nuclear launch instructions generated from the Pentagon and from Site R, or from other command posts. These messages contain the authenticated codes, which must match up to the codes contained in the war plan binders that, maybe, submarine captains keep in their safes. There is no button. There never was.

My challenge to Hollywood: Come up with different tropes.