Upticks on the Atomic Clock the Manhattan Project

By RICHARD SCHICKEL

"I never thought I'd say this to anybody, but I gotta go get the atomic bomb out of your car."

What makes this line even funnier than it sounds is that the speaker is 17- year-old Paul Stephens (Christopher Collet); that his coconspirator, Jenny, is played by a picture of innocence named Cynthia Nixon; that the exchange takes place at a high school science fair, where the competing projects involve things like soap bubbles and gerbils--and that they really do have an A-bomb in her auto.

The story of how this unlikely pair happens to be knocking at the door of the nuclear club, and what happens when the U.S. Government learns that two teenagers are making all that racket out there, has a gently realistic comic side. But it is also one of the most intelligent and gripping thrillers of recent years, a picture that transcends its WarGames genre (mainly because it avoids overt preaching and embraces humor) to set its own terms of endearment.

The film's charm lies in the fact that Paul's bomb begins ticking suspensefully not for any vast didactic reasons, but because everyone associated with it behaves in recognizably human fashion. Paul, for example, started to tinker with fissionable material down in the basement because a physicist named John Mathewson (played by John Lithgow in his best slow-burn style) is intent on tinkering with Paul's newly separated mom (Jill Eikenberry). This does not send the boy into an Oedipal frenzy, but it makes him wary when John invites him to his lab to play with a laser. The physicist has underestimated Paul, who is cannily played not as a weirdo science nerd but as a youth who likes to keep his brainpower to himself out of normal adolescent secretiveness.

The boy sure knows a pile of plutonium when he sees one, though, and he knows that one this size has no place in the medical research John is pretending to conduct. Obviously, that is just a cover story for experiments with weaponry. And so Paul and Jenny work out a way to nick some plutonium in a manner that wittily combines a sophisticated analysis of the lab's security system with kid-stuff inventiveness (their tools include a toy truck, Frisbees and a bottle of shampoo).

, Their motive is merely to alert the neighborhood that dangerous doings are taking place nearby without due process of environmental law. In hot pursuit of the security leak, the Feds apply a very broad mop to the drips, insisting that the idealists are terrorists, thus gaining an informal license to kill. Yet even here Brickman cannot resist his best impulses; he makes his villain (the subtle John Mahoney) more a man befuddled under pressure than evil incarnate. And he permits Mathewson to evolve from absentminded professor into a hero who is morally all present and accounted for.

Along the way, Brickman makes good points about nuclear proliferation and Government security without interrupting the action. Nor does Brickman, a onetime collaborator of Woody Allen's, lose his sense of humor, which delivers in glancing blows rather than kidney punches. A story of this kind is inherently implausible, but Brickman has invested it with believability and an irresistible emotional pull.