There's a shocker around every corner of "The Day Reagan Was Shot," a compelling and alarming docudrama from the Showtime cable network. If even 75 percent of the film is true, then it's a miracle Ronald Reagan survived John Hinckley Jr.'s idiotic attempt on his life and something of a wonder that the country survived it, too.

Twenty years later, we know that Reagan, nothing if not resilient, recovered from emergency surgery, became more popular than ever and went on to win a second term in the White House. In retrospect, and even though it involves the fate of a president, the crisis portrayed is obviously of less magnitude than the vicious, unprovoked attack that America suffered on Sept. 11. That is, as a national ordeal, the Reagan crisis seems almost quaint.

But the film, premiering tomorrow night at 9 on Showtime (with additional airings Dec. 12, 18 and 29), whisks you back to that traumatic day in March 1981 with crisp immediacy. It goes backstage at the crisis to show the machinations, blunders and bickering that went on in Reagan's inner circle while the beloved Gipper was fighting for his life in an operating room at George Washington University Hospital.

The inner circle, it seems, was spinning like a top. The man blamed by the film for most of the dizziness is, not surprisingly, Alexander Haig, Reagan's secretary of state and infamous for going on television early in the crisis to announce, "As of now, I'm in control here at the White House." This comforted absolutely nobody and set off one helluva hullabaloo.

Haig is played with simmering, teeth-gritting intensity by Richard Dreyfuss, a great actor by any measure and here giving a very controlled portrayal of a man who was in over his head and kept digging himself a deeper hole. Already disliked by fellow Cabinet members, he's referred to at one point by deputy chief of staff Mike Deaver (Michael Murphy) as "that lunatic," while Treasury Secretary Donald Regan (Sean McCann) laments, "He's gone mad," and worries that Haig is staging "a coup" as he attempts to run what was absurdly termed "crisis management."

The bitterest rivalry in the situation room, where the top advisers meet and argue, is between Haig and Caspar Weinberger (Colm Feore), secretary of defense. They trade insults and threats throughout the film. It's Weinberger who pops the essential question to Haig: "First of all, who appointed you to be in charge of these proceedings?" When Weinberger says he has put America's defenses "on alert," Haig explodes because this might be seen by "the Russians" (remember them?) as an act of aggression.

Since one of the executive producers of the film is conspiracy gadfly Oliver Stone, viewers may approach this with a certain skepticism. Only those with inside knowledge will know how much is true and how much is conjecture for dramatic effect. To the credit of Stone and the other filmmakers, though, "Shot" contains no swipes at Reagan, who came from Hollywood but whose politics most of Hollywood disliked.

In fact, Reagan is portrayed as the good-natured, decent and unflappable man that is his image. The odd thing is that Richard Crenna, cast in the role, makes almost no attempt to look or sound like Reagan. Obviously he didn't want to do an impersonation that might border on parody -- every comic worth his salt did a Reagan impression in those days -- but a few little Reaganesque mannerisms would have been all right. Crenna doesn't seem sufficiently presidential, or at least not Reaganesque enough.

Holland Taylor plays Nancy Reagan, to whom the media were never very kind, and fortunately this, too, is a sympathetic portrait. We see a woman of near-mythic loyalty and resolve who was not to be trifled with and who justifiably bristled when given the runaround by the Secret Service or the FBI. Taylor plays Nancy as tough but not bitchy, a welcome change from the usual savage and superficial caricature. Nancy Reagan was one of the most unfairly maligned figures of her time.

But then the movie is not really about the Reagans but about the men around them. At times, the pettiness and confusion in the situation room become darkly comic. The aides, most of them new at their jobs, come across like the Keystone Kabinet, with Haig clownishly grasping for the reins of power and barking at anyone he sees as a threat. He's even abusive to a telephone repairman: "You just shut up, and do your job, and then get the hell out."

Nearly everything that could go wrong did, from the malfunctioning phones to a scheduled NORAD defense drill being mistaken for a launch of Soviet missiles. The "football" containing the apparatus needed by the president to launch a nuclear strike was missing for a time, and later the card needed to activate it was also lost. The FBI and the Secret Service took turns blaming each other for snafus and staging territorial tantrums.

While they bickered, an intruder was able to gain access to the hospital room where Reagan was recovering, the kind of ghastly security breach that certainly resonates today.

Familiar moments are dramatized, too -- Reagan walking into the emergency room unaware of the bullet inside him, jovially telling Nancy, "I forgot to duck." William Casey, then director of the CIA, is depicted as being virtually senile. Presidential press secretary James Brady, critically injured in the shooting, is all but ignored by the filmmakers.

For all the momentousness of the event it depicts, the film is disappointingly cheapish. It was shot in Canada, so of course the hospital doesn't look like the real hospital and the streets don't look like Washington streets.

The film was written and directed by Cyrus Nowrasteh, who did a much better job as writer. His direction fails to impose the electric tension of great political thrillers like "Fail-Safe" or "Seven Days in May." Even so, and despite some stinting when it came to production values, "The Day Reagan Was Shot" hasn't even one minute that isn't gripping. What happened was bad enough; what could have happened is flabbergasting.

Holland Taylor and Richard Crenna as the Reagans in the Showtime drama about the 1981 assassination attempt.Richard Dreyfuss as Alexander Haig in "The Day Reagan Was Shot."