directed by Joseph Sargent, Spelling Television Inc./Worldvision Inc., 141 minutes .

It’s not easy to bring to life a group of scientists sitting in shirtsleeves in front of chalkboards in the desert, but this dramatization of the Manhattan Project, originally made for network television (its producer was of all people Aaron Spelling, the man who gave us “Charlie’s Angels”), is utterly absorbing. In one early scene the soft-spoken J. Robert Oppenheimer meets with Gen. Leslie Groves, the zealous military head of the effort, and tries to impress on him how little anyone actually knows about atom bombs as of 1942. At least one expert, he says, has determined that such a device would set fire to the entire earth’s atmosphere and thus end civilization.

Such scenes help establish what an amazing feat the creation of the atom bomb really was. Working under chaotic wartime conditions, with limited knowledge or experience and with the ever-present specter of Hitler building his own bomb, the Manhattan Project’s team comes across as a determined group of underdogs. You get caught up in the exhilaration they must have felt, and you can easily see how some of them lost perspective on the larger implications of their work, tossing out numbers for potential casualties as if they were counting so many electrons. Then later you share the scientists’ horror as they sit stunned in a Los Alamos meeting room watching slides of Hiroshima’s victims.

The program is well written and beautifully filmed. Most important, the acting is terrific—from supporting performances by Hume Cronyn and Hal Holbrook to Brian Dennehy as the bullying Groves and David Strathairn as the charismatic Oppenheimer, whose fragile convictions were no match for Groves’s formidable power—or, indeed, the flow of history.