By Vince Flynn

Atria. 465 pp. $25.95

There are two things one needs to know about men like Mitch Rapp, the secret agent-assassin-hero of Vince Flynn's latest novel, "Consent to Kill": They are loners and they don't play by the rules. In most espionage novels and Hollywood blockbusters, these qualities are a given, but Flynn takes no chances. On Page 4, he makes it clear: "He was a loner." As for the rule-breaking, wait for Page 46: "I don't plan on playing by anyone's rules." Those unplayed rules include logic, credibility and sentence structure, but Mitch Rapp isn't exactly a details guy, nor is Vince Flynn.

In "Memorial Day," Flynn's previous installment, Rapp single-handedly saved New York and Washington from nuclear annihilation by Middle Eastern terrorists. Such meddling hasn't gone unnoticed by some evil Saudis, who put out a contract on him, and thus grinds "Consent to Kill" for more than 400 very long pages.

Even by the cardboard-and-Kevlar character requirements of the genre, Mitch Rapp is spectacularly mono-dimensional, and his supporting cast is drawn in similarly simplistic strokes based mostly on their heritage. The German bad guy is fond of pushing his Mercedes to its limits on the autobahn while admiring its fine engineering, while the Russian drinks too much vodka and is prone to Iron Curtain homilies such as "The glorious experiment of communism has ended, and we are now left to fend for ourselves." As for the main Saudi baddie, he has a camel-shaped swimming pool -- no, really -- and the one African American Secret Service officer in the book is a fellow "who looked like a power forward for the Washington Wizards." In case you weren't paying attention, Flynn notes, "He was an imposing man. . . . You'd have to be one spectacular badass to want to take this guy on." Never seen, but alluded to, is Philip, the Rapp family's "French interior designer," who is not only French, but also . . . well . . . an interior designer and presumably not a spectacular badass.

Then there are the women in Rapp's life: Claudia, the evil sexpot assassin who comes to question her calling once she discovers she's pregnant; and Irene Kennedy, the head of the CIA, who also happens to be a Plucky Single Mother, complete with the requisite 8-year-old named Tommy.

Most remarkable of all is Anna Rielly, who's not only Mrs. Mitch Rapp but also the NBC chief White House correspondent -- or, as a senator helpfully refers to her, "a fairly well-known reporter." Imagine Andrea Mitchell in the body of Charlize Theron and you've got Anna. In Flynn's world, life as a network White House correspondent is hardly strenuous: "As long as nothing dramatic was going on at the White House, the middle of her day tended to be pretty easy. She usually took an hour to work out and was not afraid to take long lunches that usually involved shopping." At home, Rielly and Rapp have a bantering relationship: "Kill anyone?" she chirps, stuffing her latest purchases into a closet. "Not today, honey, but I've got a few hours left," Rapp ripostes. "What's in the bag?"

With that sort of espionage-meets- shopping repartee at home, it's understandable that Rapp is rather unhappy when an assassin blows his shopaholic wife to bits. Sure, Rapp had his Chesapeake Bay house fortified, but even a superspy couldn't have predicted that a devious Gallic assassin would fill the joint with propane and make his getaway on a bicycle. Fortunately, Rapp survives the explosion, as does his beloved dog Shirley (young Tommy, of course, is the one who reunites man and dog), and from that point on the lesson for would-be assassins is clear: You don't tug on Superman's cape, and you don't blow Mitch Rapp's wife to bits.

Even when "Consent to Kill" shifts from merely implausible to interminable, the plodding plotting is enlivened with a few choice bits of dialogue, none of it intentionally funny. Upon meeting the crown prince of Saudi Arabia, the U.S. director of national intelligence remarks cheerfully, "You Arabs make the best coffee in the world." And when the president finally comes around to see things Rapp's way, telling his Cabinet, "I think we are the United States of America and we need to start acting like it," all that's missing is a size-11 loafer banging on the table.

Flynn's other potboilers have made pots of money, and this should be no different. The summer travel season may be over, but "Consent to Kill" has just arrived and should be coming soon to an airline seat pocket in front of you.