(FORTUNE Magazine) – A DAY IT SEEMED WOULD NEVER COME IS FINALLY NEAR. It's the day--or, more correctly, three days--of justice, when we finally learn the fate of the three most important defendants in the scandal wave that followed the great market boom: Ken Lay of Enron, Bernie Ebbers of WorldCom, and Richard Scrushy of HealthSouth. What those three verdicts will be is anybody's guess, though that won't stop me from guessing.

Scrushy's trial has just begun in Birmingham. Ebbers's trial is scheduled to start Jan. 18 in New York. Lay will be tried twice --individually on certain counts, probably this year, and then with former Enron CEO Jeffrey Skilling and former chief accounting officer Richard Causey on other counts, probably next year.

On the truly big issues of corporate malfeasance, investor hornswoggling, and what the big kahunas can or cannot get away with, they are the three guys we care about. The trials we've seen up to now have mostly been highly entertaining sideshows. Dennis Kozlowski was accused of looting Tyco in grand style, but the company remained healthy. Martha Stewart is wintering in West Virginia because she lied about a matter having nothing to do with her company. Frank Quattrone sent an e-mail about document retention that sounded to jurors like obstruction of justice.

But now, at long last, we're under the main tent, talking about what really matters: the three most spectacular corporate collapses of the scandal era. Three major companies intentionally misstated profits by billions of dollars. Investors lost scores of billions. Pension funds imploded, leaving blameless employees destitute. Prosecutors have spent years building their cases, making plea deals as they climb the corporate ladder, preparing for the trials that will determine the only thing most Americans will ever notice or remember or care about in the legal fallout from those scandals: whether the CEOs go to jail.

The cases are remarkably similar. In each one the company became a Wall Street superstar by consistently meeting or beating analysts' profit expectations. Inevitably, one day the numbers didn't add up, and each company had to make the momentous choice of lying or telling the truth.

Each one chose to lie. In forecasting the trial outcomes, it's important to realize that no one at the companies disputes that fact any longer. The CEOs will therefore have to maintain that although massive, catastrophic, criminally bad stuff happened on their watch, they didn't direct it or even know about it.

Can they pull it off? Prosecutors have made plea deals with all three companies' CFOs--Andrew Fastow at Enron, Scott Sullivan at WorldCom, and, amazingly, all five CFOs in HealthSouth's corporate history until Scrushy was fired. They've all pleaded guilty to felonies and will surely testify at the CEOs' trials. In ordinary corporate life CEOs and CFOs talk every day, and in these cases the CFOs hold the factual ammo. So their testimony about what happened and what the CEO knew should be extremely powerful.

Even worse, at least for Scrushy, will be the effect of audiotapes. One of his former CFOs was wearing a wire for prosecutors. When jurors hear Scrushy begin a meeting with the instruction "This conversation did not take place, okay?" and then tell the CFO he must "swear to it," the hole to be dug out of is getting deep.

To counter defense attempts to make the CEOs sympathetic characters, prosecutors will play up the massive sums they were paid. We'll probably hear about Lay's multiple Aspen ski houses, Ebbers's hundreds of thousands of acres in Mississippi, and Scrushy's yacht, Rolls-Royce, and 1929 Cadillac Dual Cowl Phaeton.

The CEOs' defense attorneys, the best in America, will torture Fastow and Sullivan about their earlier protestations of innocence: "Were you lying then or are you lying now?" They'll also try to glaze jurors' eyes with the numbing details of bigtime financial voodoo.

I'm guessing that when it's all over, jurors will not believe the CEOs could possibly have remained ignorant of the crimes going on in their companies. I also have a sense that even after three years, America is still in a mood to convict a few CEOs. The prosecutors may not win on every count, but that's why they file dozens of them. Winning even a few is a victory. When those three verdicts are read, concluding the final, climactic chapter in the story of the great bull market scandals, I'm expecting a trifecta for the feds.

GEOFFREY COLVIN, senior editor at large of FORTUNE, can be reached at gcolvin@fortunemail.com. Watch him on Wall $treet Week With FORTUNE, Friday evenings on PBS.