The protocol here is a bit dicey. But let's assume it's proper to introduce "The Second Lady" first. After all, there are two of her. On the right, Billie Bradford, the blond and beautiful better half of President Andrew Bradford. On the left, Comrade Vera Vavilova, the blond and beautiful actress who wowed the KGB in Keiv. Billie Bradford speaks English perfectly. So does Vera Vavilova. k

Billie and Vera, you see, have a lot in common. You don't see? Well, take a look. "She observed herself in the mirror as she dried, the high breasts, flat abdomen, soft triangle of public hair, generous hips, full thighs. Not bad, not bad at all." Is that Vera? No, this is Vera: "Vera made a critical inspection of herself in the full-length mirror . . . What she saw was nothing to be ashamed of . . . Her breasts looked wonderful, pointed straight out, no sag . . . her stomach was flat and her hips beautifully curved yet firm." Sorry no report on the fullness of Vera's thighs; this isn't "The Book of Lists." But you can tell that Vera looks at lot like Billie -- enough like Billie that the KGB boldly snatches The First Lady and puts The second Lady in her place. And dull old President Bradford never suspects a thing.

Dull old President Bradford never suspects a thing because he's too preoccupied playing high-stakes summit poker with Soviet Premier Kirechenko, which is why Kirechenko wants Vera to engage the president in pillow talk. And frankly, dull old President Bradford wouldn't know a generous hip from a beautifully curved one if he bumped into it, although Kirechenko and Vera can't be sure of this in advance. So for Vera to keep her cover under the covers, the KGB needs some intimate information from the kidnaped Billie, whose original disinclination to perform with Russian strangers under laboratory conditions dissolves when she realizes that if her performance is, ah, unusual, Vera's will be too, and even dull old President Bradford will catch on and take immediate (or at least eventual) action to break up the plot.

You may suspect, from all of this, that "The Second Lady" is another fast-paced, action-packed, sex-fired Irving Wallace woman-in-distress pot-boiler, and it is. Reading it is the moral equivalent of eating popcorn, and we all love popcorn, particularly when it's well-popcorn and well-buttered, as Irving Wallace's novels usually are. "The Second Lady" moves along very easily and very well, but some readers will undoubtedly feel a bit cheated. The entire premise of the book -- that one woman can be substituted, undetected, for another -- requires a suspension of disbelief. It just isn't fair that the plot depends on Vera making precisely the types of slip-ups we had to assume she wouldn't make when we suspended our disbelief in the first place. Even a dumb old Soviet premier like Kirechenko might have wondered if Vera would be able to greet all of Billie's old friends by their first names.

"The Very First Lady" differs from "The Second Lady" in that Rose Keogh, unlike Billie or Vera, actually is the president when she first slips into a White House bed. In fact, the two books differ in almost every respect save the coincidence of their titles. And while Steve Dunleavy's effort is rougher than Irving Wallace's it's also more ambitious and more disturbing.

The book begins with Rose Keogh's inauguration on Jan. 20, 1985, her triumphal address and procession and her tears over the comatose figure of her husband, Sen. Sean Keogh of Massachusetts, as he is brought in by stretcher and installed in a sunny-room-turned-hospital suite on the third floor of the White House. What follows is a 400-page flashback: the life and times, not of Rose Keogh, but of Sean, tracing his career from South Boston hoodlum to presidential front-runner. Only late, very late, do we learn of the horror that struck him down and elevated his wife to the presidency as his supposed surrogate.

What Dunleavy has produced is, at its highest level, the tragedy of Macbeth with a twist Rose is the usurper, Sean the assaulted king, but unlike the mild and blameless Duncan, Sean Keogh too has blood on his hands. uAt another level -- perhaps its best -- "The Very First Lady" is a South Boston ethnic chronicle. From Sean Keogh's teenage initiation at the Erin Social Club, to his maiden efforts in the rackets, to gangland slaying amd political corruption, Dunleavy traces the rise of a tough Irish hood a "winner" who loses far more than he gains. It's a powerful story, and poignant as well, but nothing like a reprise of "The Last Hurrah" or an Irish verion of "The Godfather." Dunleavy tries too hard to make "The Very First Lady" a suspense thriller, and in a sense aims too low for his talent. He hasn't the timing needed to bring the thriller off, and fares no better than others at the impossible task of squeezing high literary art (realism) into the confines of the thriller genre (fantasy).

What Dunleavy does best is create intriguing characters -- labor bosses, mysterious priests, street punks, Brahmins, social climbers, sycophants, aggrieved women. What he does worst is put his words on paper with any polish or discernible care. Like so many journalists (he's the city desk editor of the New York Post), Dunleavy imports cliches and mini-paragraphs into a literary realm where the eye and mind roam far differently than they do across newsprint; as a result, the whole work rattles.

The only reason to dwell on these shortcomings is to emphasize, as reviewers more often should, that there's a good writer here who hasn't received the help of a good editor, and that as a result, something serious and valuable has been partly squandered. You'd think the publishing world would treat "The Very First Lady" with a bit more respect.