Double-digit inflation, high unemployment and the Iranian hostage crisis left Jimmy Carter a one-term president. Still, his watch was consequential. The US and China normalized relations, Egypt and Israel made peace and Russia invaded Afghanistan.

Beyond that, the US returned the Panama canal and in Iran the shah fell to the Islamic revolution. After 444 days in captivity, 53 American hostages were freed moments after Ronald Reagan became president.

Carter died in December, at 100. Zbigniew Brzezinski, who died in 2017 aged 89, was Carter’s national security adviser. Like his boss, who came from rural Georgia, Brzezinski was a Washington outsider. But Brzezinski was also an émigré. The son of a Polish diplomat posted to Germany, he saw Hitler’s rise, spent the war in Canada, then received his doctorate from Harvard. In 1968, as a Columbia professor, he witnessed campus unrest. His memories of the war years left him with little patience for make-believe revolutionaries.

“The protestors were spoiled brats from suburban homes risking nothing,” Edward Luce writes of Brzezinski’s take, depicting a confrontation between Brzezinski and the “rabble”. Discussion was heated, not violent. After 10 minutes, Brzezinski announced that he was returning to his office. “I have to go back and plan some more genocides,” he told the protesters.

Luce’s Life of Zbigniew Brzezinski, America’s Great Power Prophet is a bracing tome even at 562 pages, a highly readable reminder of how US and global politics looked and felt before the cold war ended. Brzezinski is portrayed vividly, warts and all.

Deeply and meticulously researched, Zbig lays out its subject’s ascent, the tumult of the Carter years and what followed. Brzezinski’s three children gave Luce “unrestricted access to their father’s extensive personal diaries, letters, and papers and his voluminous collection of documents housed at the Library of Congress”. The book’s endnotes run more than 45 pages.

British-born, Oxford-educated, Luce was a Guardian correspondent in Geneva before landing at the Financial Times, where he became a scathing critic of chumocracy and now, chief US commentator. In the late 1990s, he had a stint in government, as speechwriter to Lawrence Summers, US treasury secretary under Bill Clinton. Nowadays, he is a sometime guest on MSNBC’s Morning Joe, co-hosted by Brzezinski’s daughter, Mika.

As Luce shows, Zbigniew Brzezinski began his government career as a Democrat under Lyndon Johnson. But after Carter, Brzezinski became a political maverick. In 1988, he endorsed a Republican, George HW Bush. In 1992, alarmed by Bush’s “chicken Kiev speech” – in which the president warned against Ukrainian independence from the Soviet Union shortly before it happened – he supported Clinton.

In 2003, under George W Bush, Brzezinski vociferously opposed the US invasion of Iraq. In 2008, he backed Barack Obama over John McCain. Obama sought to distance himself from Brzezinski’s less-than-welcoming stance on Israel. Brzezinski felt stung. On the other hand, Obama made Brzezinski’s son Mark US ambassador to Sweden.

Luce devotes particular attention to Brzezinski’s extraordinary relationship with Pope John Paul II, who played a role in hastening the downfall of the Soviet Union. Brzezinski also enlisted the assistance of the pope in connection with the Iranian hostage crisis. John Paul turned to Brzezinski over the church’s presence in China.

A rapport developed, Brzezinski’s command of the Polish language helping things along. In June 1980, Carter visited the Vatican. The night before the big meeting, Brzezinski and Col Les Denend, an aide, received a mass “for the ages”. As they left, “the pope grabbed Denend’s arm and told Brzezinski, ‘I should have a colonel as my assistant, not you. I am keeping him.’”

The following day, “Brzezinski and John Paul II spent seven hours in conversation,” Luce writes. “They continued talking while [the Pope] gave Brzezinski and Denend a private tour of the Sistine Chapel.”

Luce considers the depth of Brzezinski’s Catholicism. A product of a Jesuit education, he appears to have developed doubts. On his death, his children scattered his ashes in a Virginia forest. He had left no instructions.

Brzezinski’s rivalry with Henry Kissinger marked the lives of both men. Kissinger, a Jewish refugee from Germany, arrived in the US in September 1938. He served in the US military, unlike Brzezinski, then received tenure at Harvard, then became national security adviser and secretary of state, under Nixon and Ford. Nelson Rockefeller was Kissinger’s first political patron. David Rockefeller, Nelson’s brother, stood behind Brzezinski.

Kissinger was pessimistic, viewing the US in a state of decline. He also believed the Soviets were a permanent fixture of the “global landscape”. Brzezinski judged the Soviets to be sliding. As Luce puts it, he thought “Washington’s goal should be to hurry them along.”

Luce also details and dishes on the historic Camp David peace talks between the US, Egypt and Israel.

Carter’s rapport with Anwar Sadat of Egypt was deep and warm. “My chemistry with him is good,” Carter said. But Carter possessed no love for Menachem Begin of Israel, calling him a “psycho” in comments to Rosalyn Carter, his wife. “The coldness between [Begin and Carter] was tangible,” Luce writes. Carter reportedly told Brzezinski: “Begin is devious to the point of lying.”

And yet Carter drew parallels between Brzezinski and Begin, who was also born in Poland. “You’re just like Begin,” Carter is quoted as telling his national security adviser. “Brzezinski took that as a compliment,” Luce writes, quoting a note from Brzezinski to self: “I think this remark was in some respects quite true.”

In old age, Brzezinski looked on as US politics, and foreign policy, took a worrying turn.

“A major country like the United States has to have a broadly conceived program for effective international action, influence and cooperation with others,” Brzezinski said in March 2017, discussing Donald Trump.

“I see nothing of the sort emerging from the administration and least of all from the president, who in my account has not given even one serious speech about the world and foreign affairs.”

Brzezinski died two months later.

• Zbig is published in the US by Simon & Schuster