[In the following review, Rabinowitz examines Heart of a Soldier, James B. Stewart's biography of Rick Rescorla, the chief of security at Morgan Stanley in New York City, who was responsible for securing the evacuation of 2,700 of his co-workers while losing his own life in the effort.]

The subject of a number of Sept. 11 pieces, Rick Rescorla is nonetheless a name unfamiliar to most Americans. That could soon change with the publication of Heart of a Soldier, James B. Stewart's stunningly detailed history of the British-born Rescorla, who became an American citizen and fought with conspicuous valor in Vietnam—which was, as it turned out, not the last battleground to test this remarkable character.

Long after Vietnam, he took a job for which he was eminently suited—that of security chief at the brokerage house of Dean Witter in New York, which would eventually merge with Morgan Stanley. Rescorla was suited to a number of other jobs, to be sure—he had earned a law degree and written a textbook on criminal law. But it was in the role of security chief that Rescorla engaged in his final battle—as a huge presence who brought all his strength and resources of spirit, all his discipline and verve, to the struggle to get his charges out alive when the planes struck the World Trade Center.

When it was all over it was clear that Rescorla had evacuated 2,700 Morgan Stanley employees—all but six—and that he had died trying to save the rest. With this news, Dan Hill, Rescorla's longtime friend and fellow soldier, thought to comfort the dead man's widow. He wanted to tell her, as he believed, that if Rescorla had come out of the building alive and discovered that someone back there had died whom he hadn't tried to save, he would have had to commit suicide.

Clearly there was more to be told about the man—more than had been told in James Stewart's New Yorker piece focusing on the late-life romance that came to Rescorla before death found him in the Sept. 11 inferno. The rest is what Mr. Stewart sets out to provide in this history of three lives destined to be joined. In addition to Rescorla, there is Mr. Hill and Susan Rescorla, the divorced woman he met when he was 59, to become his wife for a time all too brief.

Mr. Hill, who knew Rescorla best and longest, is a figure of no small interest. As early as 1988, Rescorla asked his old friend to come to New York to check into the possibility of an attack on the World Trade Center. Rescorla had become concerned that the World Trade Center was an obvious target. A decorated combat veteran, Mr. Hill had seen action all over the world and worked as an intelligence agent. His assessment of the World Trade Center's vulnerability was alarming. He noted that a truck loaded with explosives could easily be brought into the unguarded underground parking levels.

Port Authority officials were not impressed with these warnings, transmitted to them by Rescorla, who was essentially informed that he should mind his own business and stick to security on the floors for which he was responsible.

Mr. Stewart reports that Port Authority officials had similar warnings from their own staff but had concluded that “world terrorism had subsided.” After the 1993 World Trade Center attack, involving a truck with explosives in the sub-basement, just as Mr. Hill and Rescorla had warned, the two friends prepared a report arguing that Islamic terrorists would surely plan another attack, this time possibly with an explosives-laden plane crashing into the towers. The Port Authority officials again showed little interest.

Still, Rescorla knew what had to be done, what his life's experience had taught him. At Fort Benning, Ga., Rescorla's men had had to do twice the work that other platoons did—if others marched five miles, they marched 10. When they thought they were finished for the day, Rescorla made them sing the battalion song. They complained, but they marched, they sweated and they sang, and they emerged from their training, lean, hard and confident.

As Morgan Stanley's security head, Rescorla designed an evacuation plan and demanded that employees practice the drill regularly. This was the plan they followed when the first plane struck the other tower. With Rescorla urging them on through his bullhorn, Morgan Stanley employees began the trek down the stairs exactly as they had trained, in pairs, even as building officials were telling them that they should stay at their desks, that the building was secure.

The signs of a writer's engagement with his subject always make themselves known, and this gripping history is no exception. Everything about it testifies to Mr. Stewart's ardor for his subject, his relish in every detail, which readers are likely to share—though some may find themselves wondering if it is entirely necessary to know what Susan had for breakfast, what she said to her mother, what Dan Hill said to his wife or thought about his father.

About Rescorla himself one can never learn enough. The final chapter is titled “A Day to Be Proud”—an evocation of one of Rescorla's last words to his charges. “Today is a day to be proud to be an American,” he told them through his bullhorn. As searing a narrative as we have had of that day, the chapter follows the workers fleeing to safety. In the streets, three of the saved women workers join hands to pray aloud: “Lord take my bosses and coworkers out of there.”

In Vietnam, Second Lt. Rick Rescorla told his men: “If you believe in yourselves and believe in me, we will come through anything.” Self-belief doesn't always work that way, of course. At Morgan Stanley most came through Sept. 11.

Rescorla, who ran upstairs to look for stragglers, did not. He did not precisely because he believed in himself and in the values of duty and courage he had chosen for his life—which Mr. Stewart has so movingly rendered.