Disturbingly inadequate, yet also inescapably moving, "Wallenberg: A Hero's Story" tells less than it should about the Swedish-born diplomat who bravely and with considerable success fought efforts of the Third Reich to exterminate Hungary's Jews.

While it ends on an inexcusably abrupt and cryptic note, this is nevertheless a great and gripping story, and a film that enhances rather than diminishes the legendary heroism it dramatizes.

The two-part, four-hour NBC movie, at 9 tonight and tomorrow night on Channel 4, also reveals Richard Chamberlain at the height of his acting powers, which here seem considerably more formidable than in previous mini-series appearances like "Shogun" and "The Thorn Birds." He has found some sort of poignance in his own good looks, and that serves him well as Raoul Wallenberg, who must have felt a certain embarrassed guilt about accidents of birth and fate that seemed to protect him from the hell raining down on Europe in the 1940s.

According to the film, Wallenberg's mission was something on the order of noblesse oblige until a moment of harrowing realization. This shock to his consciousness, beautifully shot by director Lamont Johnson, occurs in the first quarter of Part 1, when Wallenberg is on his way to Hungary and sees from the window of a train another train on adjacent tracks, and in the blur of boxcars moving past perceives supplicating hands, outstretched arms and helplessly sobbing faces, and he realizes who these people are and what sort of horror is being perpetrated on them. His resolve is stiffened and, similarly, the film's grip on one's attention tightens.

In Part 2, there is a comparably traumatic sequence. Despite his efforts to frustrate the Nazis in their pursuit of Jews in Budapest and throughout Hungary, hundreds are being marched off to trains that will take them to camps and possibly to torture and death. It is a grimly rainy day, and fog swirls around the seemingly doomed, huddled, trundling throng, and Wallenberg says, "Perhaps we are witnessing the death of God himself." The specter of the Holocaust should never be invoked for the purpose of cheap melodrama. Here it is not.

Gerald Green, who in fact wrote the NBC mini-series "Holocaust," is also the author of the "Wallenberg" script. It tends to be a grab bag of facts, incidents and fictionalizations, sometimes abruptly disorganized, but it makes a powerful cumulative impression, and it is faultlessly serious. The film opens on April 30, 1944, Walpurgis Night, and when we first meet Wallenberg, he appears a glib aristocrat, not the stuff of which heroes are made. He does a baggy-pants impression of Hitler at a party attended by Nazi sympathizers. A Jewish friend, Kalman Lauer (Peter Capell), helps raise his awareness.

From the thankless task of portraying mass-murderer Adolf Eichmann, actor Kenneth Colley fashions a daunting accomplishment. "The final solution has been set in motion," he declares, and Wallenberg leaves his home and his mother (Bibi Andersson) for Budapest, where he embarks on a recklessly bold scheme. Wallenberg's plan is to issue to as many Hungarian Jews as possible papers of Swedish citizenship that will, with Sweden's status of neutrality, offer at least temporary protection.

In a Budapest nightclub, where a semisultry songstress sings an American tune that comes out as "Shtormy Veddair," Wallenberg and Eichmann meet. Whether they actually had as many face-to-face confrontations as are depicted in the film is probably unimportant. These are tense scenes. Colley makes Eichmann sinister in subtle, not just obvious, ways. In Part 2, over a supposedly cordial cocktail, and with the end of the war now imminent, Wallenberg asks Eichmann, "Shall we drink to the death of monsters?" When he has left his office, Eichmann growls the order, "I want that Jew-lover dead before the day is over." Certainly it is not the purpose of the film to allege that those with the power to do it did everything possible to aid the Jews. "I'm not sure the Vatican shares our concern," Wallenberg says to a monsignor, who replies, "I'm afraid there are always political considerations." In celebrating the fact that thousands of Jews were saved by Wallenberg's efforts, the film does not lose sight of the fact that millions more died.

Melanie Mayron effectively plays an embattled refugee in the film, and a young discovery, a gypsy orphan known as Bogdan, is a memorably haunted, accusing presence as her little boy (he learned his few lines phonetically). Stuart Wilson plays Baron Kemeny, a Hungarian official pressured by the Germans and the Wallenberg forces, and caving in to the former, and Alice Krige, the mesmerizer of "Ghost Story," is mesmerizing again as Baroness Kemeny. Her attraction to Wallenberg may get too much screen time and seems to suggest the view that humanitarianism can be sexy, but Krige gives the character a meaningful dignity.

Ernest Gold, who many years ago wrote the score for "Exodus," composed the music for "Wallenberg," which was photographed in England and Yugoslavia by Charles Correll.

All these contributions are praiseworthy. Where "Wallenberg" weakens, among other spots, is in the cliffhanger ending to Part 1, designed a little too baldly to lure viewers back the next night. And where it collapses is at its conclusion, when the war is over and the Russians are "liberating" Hungary and, out of nowhere -- the dramaturgical nowhere -- descend upon the car carrying Wallenberg out of the country and arrest him. The screenplay is clumsily incommunicative about what is going on and why Wallenberg was arrested (it was apparently on suspicion that he was an American agent, though even that is fuzzy here). After four hours of watching him evade Nazis, an audience is owed more of an explanation for this jolt.

It makes the film seem much too soft on the Soviets, who threw Wallenberg into prison and now claim he died there in 1947. Some believe he is still alive. For four hours on NBC this week, at least, he will be. The movie is flawed, but it is entirely worth seeing.