Last Thursday, April 30, marked the 40th anniversary of the fall of Saigon, and the unhappy end to America’s long adventure in Vietnam.

In September, in anticipation of that anniversary, Rory Kennedy (daughter of Bobby and Ethel) released Last Days in Vietnam, a documentary chronicling South Vietnam’s final hours and the evacuation of some 130,000 South Vietnamese as troops from the communist North swept in. The documentary premiered on PBS last week, and is now available on DVD and for viewing online.

The story of South Vietnam’s collapse is eerily relevant. How is peace kept? Are America’s promises dependable? Such questions were then, and remain now, far from academic. The humanitarian responsibilities of warfare remain long after the fighting is over.

And so while there is much to recommend Last Days in Vietnam — much of the footage is simply stunning — perhaps most remarkable is that the film manages to raise such questions without peddling easy ideological answers. It is not, as one has come to expect of Vietnam retrospectives, an anti-war propaganda piece. It is, instead, a straightforward story of people, of very human beings in Saigon and in Washington, D.C., who made costly mistakes and noble sacrifices.

The film features no narrator; everything is related in interviews — with Marine guards at the American embassy in Saigon and Marine helicopter pilots, with CIA and State Department officials on the ground in the country, and with natives of South Vietnam, whose fates depended on American logistics. So it is from them that one hears about, for instance, the conflicted American ambassador to South Vietnam, Graham Martin, a devoted anti-communist who refused — or was unable — to see the danger of the situation as the North Vietnamese army rolled south, and so refused to order an evacuation until it was almost too late — but who acted with utter self-sacrifice afterward, doing everything in his power to get as many South Vietnamese as possible out of the country. One learns, too, about the American soldiers who defied orders to help save natives, but who were also forced to push desperate South Vietnamese away at the embassy gates; and about the men and women from South Vietnam who exercised extraordinary bravery and cunning to get their families to safety.

Ms. Kennedy tells a simple tale of human fallibility, and of good people doing their best under harrowing circumstances. They remind us that the final duties — above winning or losing, above survival — are to honor, and to one’s neighbor.