THE SUM OF ALL FEARS, by Tom Clancy, G.P. Putnam’s Sons, 798 pages, $24.95.

In “The Sum of All Fears,” his most convoluted epic to date, Tom Clancy takes his unperturbable hero, Jack Ryan, on a globe-trotting expedition that ultimately spares the United States and Soviet Union a nuclear holocaust. This novel, unfortunately, does not spare the reader any confusion as to what’s happening and when.

Clancy, who created Ryan in “Hunt for Red October” and starred him in three of his succeeding four novels, works with a single premise in “The Sum of All Fears”: During the October 1973 Arab-Israeli War, the Israelis lost an aircraft and a nuclear bomb.

The bomb bellied into a Syrian farm, where a Druze farmer buried it. About 20 years later, some Arab terrorists retrieve the bomb, which the frost by now has heaved to the surface. With assistance from a German scientist, the Arabs redesign the bomb. With help from an American renegade and a German outlaw, the Arab terrorists deliver the bomb to the Super Bowl — and start a shooting war between the United States and the Soviet Union in Berlin — and drive the American president nuts — and almost scuttle the Middle East peace hammered together by Ryan, the United States and the Vatican — and …

… let the reader wander across the globe while trying to understand a book that incorporates plots from “Hunt for Red October” (submarine warfare), “Red Storm Rising” (the armored clash in Berlin), “Patriot Games” (Ryan meets with Prince Charles in London), and Clancy’s two other novels. Clancy draws so heavily on his past works, the reader who hasn’t perused the first five Clancy novels is handicapped in understanding “The Sum of All Fears.”

If Clancy had stuck to his plot — getting the terrorists’ nuclear bomb out of the ground and into Mile-High Stadium in Denver — “The Sum of All Fears” would have worked. Even the subplot, in which an exhausted and overworked Ryan battles to save his marriage and successfully outwits the president’s national security adviser (and mistress), flows well.

Clancy’s latest novel bogs down in its minutiae. In a subsubplot, the nuclear submarine USS Maine stalks a top Soviet sub in the Gulf of Alaska. By the time the Soviets torpedo the Maine (shades of 1898), the reader wonders what sub warfare has to do with terrorists nuking the Super Bowl.

Another subsubplot involves the terrorists, a dislikable bunch of guys drawn from the Red Army Faction, the American Indian Movement, and shadowy pro-Iranian groups. Clancy expends great detail in explaining how the terrorists concoct their bomb. Along the way, he radiates a guard, slaughters a captured Soviet intelligence agent and the German scientist’s wife, butchers the AIM member, and gets the two surviving terrorists safely out of Denver before their nuclear bomb evaporates Mile-High Stadium.

All this endless detail considerably slows the action.

Fortunately for the good guys, the terrorists’ weapon doesn’t work as well as planned, but the nuclear explosion sends the United States and Soviet Union to the nuclear brink. As the president and his NSA crack under the pressure, and warfare erupts in Berlin, the Med, and the Gulf of Alaska, Ryan forces a constitutional crisis to save the day. He’s aided by a blizzard, a traffic accident that kills an Air Force general, a supportive vice president, and a friendly Soviet premiere. It’s amazing how well all the technology works and how the right people don’t fold in the clutch.

Another reviewer once noted that Clancy’s odd-numbered novels are always his best, while his even-numbered novels fall short. “The Sum of All Fears,” which is No. 6, reads more slowly than “Clear and Present Danger,” an excellent No. 5. Save yourself $24.95 plus the 6 percent sales tax and get “The Sum of All Fears” at your local library.

Brian Swartz, who works for the Bangor Daily News, remains a loyal fan of Tom Clancy.