Plot is Everything

While doing some online studying on writing good mystery novels, I ran across an article written by Ginny Wiehardt, titled "Top 10 Rules for Mystery Writing." Good article, just click on the title if you want to read it. She puts as number one in importance, the plot. Here's an excerpt from the article:

1. In mystery writing, plot is everything.
Because readers are playing a kind of game when they read a detective novel, plot has to come first, above everything else. Make sure each plot point is plausible, and keep the action moving. Don't get bogged down in back story or go off on tangents.

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I tend to agree. Certainly in any fiction genre, plot is of tremendous importance. But in the mystery novel it takes front and center stage, more so than say, the romance novel - where the same old "boy meets girl and they eventually fall in love against all odds and probability" plot will work just fine. Back story all you want, go off on a romantic and/or dangerous tangent here and there if you please, so long as the characters and situations are complex and interesting enough, and it all ends in a steamy lovemaking scene with the promise of living happily ever after, you're fine. Or the spiritual/inspirational novel where the messages delivered, if powerful and insightful enough, can be of more importance than a super duper move-it-always-straight-forward plot interlaced with several sub-plots and all kinds of twists to it.

Not so in the mystery novel. The "guessing game" aspect, the beloved "twists," those smack yourself on the forehead "aha!" moments when you realize how cleverly the author has misdirected your attention and/or had you despising the wrong "obviously guilty" character up until now - this is the quintessential stuff of good mystery writing. A superior plot is absolutely key and the mystery novel without one is doomed to mediocrity without it.

That's my opinion. What's yours - and why?