"We have a name in the studio," Alfred Hitchcock once explained, "and we call it the 'MacGuffin.' It is the mechanical element that usually crops up in any story. In crook stories it is most always the necklace and in spy stories it is most always the papers."

In this summer's Larry Craig saga, the MacGuffin is his specific behavior in the Minneapolis airport bathroom that led to his arrest for lewd conduct, the reduced charge of disorderly conduct, his guilty plea and payment of the $575 fine, his intention to resign, and his most recent decision to attempt to withdraw his guilty plea and remain in the Senate.

The audience doesn't care about the MacGuffin. We are interested in the characters themselves: who they are, what makes them tick, how they get along with others. It's the same with Craig. We just want to know what the facts mean about him as an individual.

Is he a criminal who routinely intrudes on people's privacy in bathrooms?

Is he trustworthy enough to remain in public office?

The problem is that Craig's MacGuffin is poorly defined, violating all of Hitchcock's precepts. What really happened in the bathroom? It's not clear. Craig probably told some fibs in the transcript, such as claiming his hand never went under the separator but that he was trying to pick up a piece of paper. (Can you remember the last time you picked something up off of the floor of a public bathroom?) The cop probably made some mistakes too, like confusing which hand of Craig's he actually saw. Craig basically admitted to all the other details but he was adamant that it was his right hand, not his left, that wandered, a weird sticking point unless it was the truth. Plus, the cop probably stopped too early: If the government is running a sting, they better be damn sure that they get all the evidence they need. All this cop got was innuendo. Any jury would likely acquit Craig.

But the purpose of the police sex sting wasn't a trial. They knew they were dealing with people far more likely to care about their own privacy than a few hundred dollars in fines—a chilling indictment on the sting itself.

In such a "shakedown" sting, the cops don't need as much as they would to actually convict.

The cop essentially offered an implicit deal to Craig: pay the fine, and the media won't find out. Craig paid the fine but the media found out anyway. Is it any surprise Craig feels his deal was violated? Of course he now wants to withdraw his guilty plea.

In a Hitchcock movie, we'd know exactly what happened in the bathroom. But what we are witnessing may be more like a Quentin Tarantino film. One of the most famous MacGuffins of all time is Marcellus Wallace's briefcase in Pulp Fiction, whose contents are never disclosed. Some speculate it contained his soul.

And we must speculate what Craig did.

The reason we must speculate is because the cops didn't do as thorough a job as they could, and should, have done.

If you accidentally bump someone's foot under a stall, should you expect a cop's hand to reach underneath and hand you a business card? It's probably enough to convict Craig if the man in the other stall was a victim, but probably not enough if the man is a cop.

In either a Hitchcock or a Tarantino film, we don't care what the MacGuffin is, but we need to feel it is well-built. Otherwise we feel anxiety. We feel the filmmakers failed in their contract with us, the audience.

Similarly, if the evidence against Craig is not well-built, we feel the police may have failed in their contract with us, the citizens.

And that's the scariest horror of all.