By Ty Burr
February 04, 1994 at 05:00 AM EST

What makes a person kill a President? Politics? A quest for fame? An attempt to right imagined wrongs? It’s a vexing question; consider that the signal mystery of the last 30 years — the enigma that bollixed a generation and launched a thousand conspiracy theories — is Lee Harvey Oswald’s exact motive.

The unknowable makes for lousy box office, though, and political assassins have never ranked high as fictional villains. In fact, the Clint Eastwood summer hit In the Line of Fire is the rare mainstream movie that paints an ostensibly real portrait of a man with a gun and a grudge — and then only from the Secret Service’s point of view. But is Mitch Leary (John Malkovich) just another bijou bogeyman? Now that Fire‘s on tape, it’s worth watching in the light of other videos about political assassins.

Start in 1954, with Suddenly (Nostalgia, unrated, $16.95), a little-remembered thriller that casts Frank Sinatra as Johnny Baron, a soul-dead killer who plans to intercept a train carrying the President of the United States through the desert burg of Suddenly, Calif. The uncomplicated patriotism of Johnny’s small-town hostages is typical of the Eisenhower Era: The message is pro-gun, pro-Korean War, anti-Communist. The movie’s assassin is more complex. A gangster hired by unnamed foreign powers, Johnny professes to be apolitical: ”I got no feeling against the President. I’m just earnin’ a living.” At the same time, he’s clearly a nutjob. When Johnny addresses the camera in paranoid tirades, Sinatra puts across a lanky, inarticulate menace: You can feel his fevered brain trying to squeeze angry thoughts out.

Suddenly is realistic in that sense, but moviemakers didn’t pick up on the lone-psycho theory. The next film to have an assassin as its focal character, John Frankenheimer’s The Manchurian Candidate (1962, MGM/UA, unrated, $19.95), still insisted that a high-level cabal would be necessary to off a Presidential candidate. Of course, Candidate (costarring Sinatra) goes off the deep end, enlisting Chinese Commies, right-wing senators, and the hero’s demonic mom (Angela Lansbury) in its blackly comic plot. But while Raymond Shaw (Laurence Harvey) may be a snob, he’s not a born assassin. On the contrary, he’s a brainwashed assassin, programmed to snap into killing mode whenever he plays solitaire. His helplessness — he whimpers to a friend, ”They can make me do anything, can’t they?” — is the human tragedy at the center of a wickedly smart roller-coaster ride.

The first movie to look deep into the eyes of a would-be assassin and see a truer chaos is Martin Scorsese’s Taxi Driver (1976, Columbia TriStar, R, $19.95). A portrait of a loner (Robert De Niro) whose stunted hurt gathers steam as it bounces off beautiful, distant women and uncaring strangers, Driver hasn’t dated in the least. It could be the story of last December’s Long Island Railroad gunman. Actually, screenwriter Paul Schrader was influenced by the diaries of Arthur Bremer — whose gunshots paralyzed Alabama governor George Wallace — and the movie gave off a ghoulish echo when John Hinckley Jr. took its save-Jodie Foster subplot with pathetic literalness. Brutal and pared to the bone, Taxi Driver grows more relevant with every new random massacre.

In comparison, In the Line of Fire is a backstep. Sure, the movie’s a rich confection that merges suspense pyrotechnics with more sober dramatics befitting star Clint Eastwood (playing a Secret Service agent who dropped the ball in Dallas back in ’63 and has a chance to atone 30 years later). And in the sardonic, inventive hands of John Malkovich, assassin Mitch Leary is fiendishly charismatic: a renegade CIA spook bent on revenge against a country and a government that screwed him over.

In the Line of Fire is fine pop entertainment, in other words, but here’s why it falls short in the credibility department: It gives Leary a reason. It makes him a master of disguise and a witty, worthy opponent of Eastwood’s Frank Horrigan. It lets Malkovich indulge in flashy gonzo behavior (like wrapping his lips around Horrigan’s gun in one scene). It creates a great — if undeniably twisted — movie villain.

Oswald would probably have loved to have seen himself portrayed this way — the mad genius at the center of the plot. So would Bremer, or Hinckley, or Charles Guiteau, who shot and killed President James Garfield. Definitely John Wilkes Booth — the man was an actor, after all. But the reality was that all of them (Booth excepted) were the kind of faceless losers who keep it all in, whose rage, when it finally erupts, prompts wonder from neighbors and schoolmates. They would make drab movie bad guys, these real assassins. Giving them credit for anything more than luck and sick determination is the worst way to understand or prevent them.

In the Line of Fire: B+; Suddenly: C; The Manchurian Candidate: A; Taxi Driver: A-