SUMMER READING ISSUE : Out of the Ordinary : FICTION : MY REAL NAME IS LISA,<i> By David Alexander (Carroll & Graf: $21; 280 pp.)</i>

Novelists love to put ordinary people in extraordinary situations. To take a protagonist out of his own world and put him into a strange, even dangerous or violent circumstance is a delicious temptation for the writer. The result can be humor or suspense. Eric Ambler, a master at this game, has, for more than 50 years, created rather retiring, bumbling and bookish types and plunged them through odd circumstance into international intrigue with agonizing and riveting consequences.

This is also the structure of “My Real Name Is Lisa,” David Alexander’s third novel. Instead of Ambler’s geopolitical milieu, Alexander’s extraordinary situation is the sum of every parent’s fears--the horror of kidnapped child.

His ordinary person is Peter Howard, president of a software company. On his way to a business meeting, Howard takes an unfamiliar exit off the freeway in search of a headache remedy and finds himself in a seedy little grocery store, face to face with a kidnapped child and the pedophile who is holding her captive.

Howard sees something in the little girl’s eyes that makes him aware that something is very wrong. When the man she is with acts oddly and threateningly to the child, milquetoast computer nerd Howard (who conveniently learned to box after a bully tormented him in school) follows their car, kicks the nasty man in the privates, narrowly avoids being shot and takes the girl, Lisa.

So far so improbable, but improbable at an acceptable level. What follows, though, is the crux of the plot, and it is so improbable as to require utter suspension of disbelief, which is why the plot frays and finally unravels. Peter Howard, this quintessentially ordinary business executive, having rescued a little girl from a monster, does a supremely illogical thing: He does not call the police.

Instead he embarks on a wild cross-country odyssey with Lisa, during which, among other adventures, they are captured by her real kidnappers, an evil tripwire Vietnam veteran--who masterminded her snatching and sold her to the villain Howard has already vanquished--and his stupid henchman who actually did the taking.

Everything that happens on this journey is breathtaking and cinematic. Alexander has a penchant for creating chaotic interactions, but they are too baroque to be believed. Howard loses his credit and ATM cards when they are captured. Does he simply call and get new ones after they escape, as most affluent executives would do? No, he turns into a rather scruffy character trying to get Lisa to her rightful home with no money.

This is convenient for plotting. They meet an astonishing array of characters, including a pot-growing farmer who talks them into taking a load of bogus hay bales down the road in a stolen truck, which they wreck, and a wacky, saintly retired minister driving a ’56 Chevy (whose life Howard also manages to save). See what I mean?

It’s a nice try. The subject of child kidnapping is absorbing and deeply troubling and should be a powerful backdrop for this sort of book. But the story palls and the suspense fizzles. You know Howard will get Lisa home--it is too quixotic a quest, too noble an effort to be denied. Too many of the minor characters here are stereotypical, especially the bad guys, from the wife-beating white-trash loser who punches out the black minister to the kidnapper himself, whom Howard manages to kill. Even Howard’s character is somehow too pat, what with his work-related travails and successes and his divorce that left him scarred but sensitive.

Lisa is probably the best, most interesting character in the story, and her journey home is entertaining. It’s a pity it is not more believable.