First there was Mario Puzo's crude but potent 1969 novel, The Godfather, the seminal portrait of charismatic Mafia boss Vito Corleone and his three quarrelsome sons. Then in 1972, with a screenplay cowritten by Puzo, Francis Ford Coppola transformed the pulpy opus into an indelibly radiant film, a powerful legend of the American immigrant experience, which he extended and deepened two years later in his extraordinary sequel, The Godfather Part II. The Corleone saga from poverty to prosperity to decline has been told, retold, etched in the national consciousness, and even pushed beyond its limits in 1990's dismal Godfather Part III.
But Random House decided to milk the franchise and two years ago commissioned a sequel. Now comes Mark Winegardner's The Godfather Returns, a fussy, earnest homage to the original Puzo potboiler. Set between 1955 and 1962, the book fills some gaps toward the end of Puzo's novel and embroiders on the dark mythology of Coppola's streamlined films, expanding needlessly on the motivations of established characters and inserting byzantine new story lines.
In the final pages of Puzo's novel, the traitorous Corleone family operative Salvatore Tessio is murdered, discreetly, behind the scenes. Winegardner's narrative begins by describing, up close and hideously, what actually went down that night in 1955: Small-time Corleone wiseguy Nick Geraci (a new creation) is ordered to shoot Tessio, then slice off his head. Geraci complies, reflecting: ''How is sawing off the head of a dead father figure so different from separating a succulent turkey leg from the carcass? A thicker bone, true, but a bone saw is a better tool than some knife your brother-in-law got you as a wedding present.''
The philosophical hitman begins collaborating closely with boss Michael Corleone, who is trying to go legit, largely to placate his wholesome New Hampshire-bred wife. But Michael and Nick gradually slide into one of the tetchy, unspoken feuds familiar to anyone who's watched Tony Soprano negotiate, season after season, with a rotating cast of doomed Tony B.'s and Ralphie Cifarettos.
Meanwhile, Winegardner gives a prominent role to Sonny's daughter, Francesca, who goes to college, marries a creepy ladies' man, and gets in touch with her violent inner Corleone. And Michael's pathetic brother Fredo gets a dark secret to account for his sniveling cowardice. Though Fredo ''knocked up half the showgirls in Vegas'' and married a sexy Hollywood star, he often finds himself doing ''the other thing.'' In other words, he's a ''fruit'' and gay self-hatred has made him volatile and unreliable.
This facile psychosexual analysis is just the kind of cheesy twist that Puzo might have conceived. And Winegardner writes like he's channeling Puzo, with a brisk pace, extended sex scenes, explicit gore, and pedestrian prose studded with trite homilies (''No matter how hard you beat a donkey, it will never become a racehorse''). But where Puzo had complete freedom to take his plot in any direction and produced a strong, original story Winegardner, tightly constrained by the Godfathers that came before, has written a timid, derivative novel.