If the Jackboot Fits . . . : RICHARD’S FEET <i> By Carey Harrison (Henry Holt: $22.95; 672 pp.) </i>

This first, sprawling novel of Carey Harrison is the saga of an English scoundrel obsessed with the violent passion of the German soul. This novel begins in 1968, with Richard Anstruther Thurgo, R.A.T., a.k.a. Ratty to his school chums, at age 50, poised to find the son he abandoned in England 20 years before, when he stole a chance to switch identities with a corpse in Spain.

Reborn on the lam, he loses himself in the teeming, amoral energy of postwar Hamburg’s red-light district. This book deals with those memories, beginning 37 years before when Thurgo was a tall, gawky and unlikable adolescent. That he remains fascinating while his actions often repel is comparable to the sensation of reading Robert Caro’s account of the machinations of young Lyndon Johnson.

This lusty saga starts in earnest in 1936; Thurgo is a horny adolescent, paradoxically cynical and naive, serving as a go-between for the romantic Maggie Trimble and her two suitors--Richard’s cool and manipulative arms-salesman brother Alec, and a German aristocrat, Count Peter von Lutzow-Bruel--as they courted at the count’s castle in Mecklenburg, all in the shadow of the coming Nazi horror.

Ratty forcibly seduces the count, and has a violent, sexual encounter in the woods with the peasantish Herta, who later returns to haunt him in Hamburg. And as a result of a war romance, Richard marries Maggie’s less romantic sister, Molly.

There is much, much more, but you start to get the idea that Harrison was determined to write a truly big book, and sometimes this ambition gets in the way.

The premise of the novel has a compact grace that suggests a much shorter, sharper and ultimately less ambitious book--a spy thriller. Richard Thurgo seems to be dead and buried a third of the way through the novel. A pair of feet are buried in Highgate Cemetery in London, brought back from Spain by Richard’s widow, Molly, in 1948.

The feet, preserved by boots belonging to his late uncle Col. Tom Thurgo--a key postwar Nazi sympathizer and soldier of fortune--were all that remained of a man burned beyond recognition in a wrecked Jeep in Malaga in spring 1948. There is a question whether the man in the Jeep was actually Martin Bormann, a.k.a. Thomas Schaefer. Thurgo uses Schaefer’s ID to start a new life, changing his name once again to Reinhard Sacher, a former SS officer--a life in which he becomes embroiled as a counterspy in divided Germany under the manipulative thumbs of Kim Philby and Norby Walters.

This, in turn, is for Thurgo merely the price of admission to a fantasy life as the right-hand man for Wolli Zimt, the “Al Capone of Hamburg,” amid the gangs in Hamburg’s wide-open Reeperbahn, “The World’s Most Sinful Mile.”

It is strangely exhilarating to see Thurgo’s primal energy, almost without conscience, survive so many of his much more morally sensitive friends. While he admires the count’s fatal commitment to a failed assassination attempt on Hitler, Thurgo becomes a gangster among the gangsters, ready for murder and worse.

The mystical references to time throughout the novel are as hard to comprehend as it is difficult to endure the long subplots. “Richard’s Feet” has few moments of philosophical insight or moral transcendence--not a great payoff for such a long book. The one key lesson--hardly unique--in Thurgo’s obsession with his own violent nature seems to have been that Nazi Germany was not an inhuman aberration:

“I didn’t enjoy my adoptive role because I secretly approved of Nazi ideas and Nazi behavior. Their cruelty continues to enrage me and to fascinate me as it fascinates us all. . . . These were thoroughly human atrocities (good human atrocities I almost want to say; true to our barbaric nature) and unless we recognize them as our own, we only hasten their return in another uniform.”

“Good human atrocities” indeed! Such ravings threaten to stop us from caring about the narrator, as well as for other characters who are finely wrought and consistently interesting throughout. “A ghoulish image of Walpurgisnacht? Not at all, believe me,” crows Thurgo about postwar Germany, about a people rebuilding, starting with a blank slate.

“I felt more aroused than I ever had in my whole life . . . and you must understand this was not a demonic Germany; it was just a place, a city like any other, now more real and powerful and abundant by the presence of death, not by its aftermath but by its vital, ordinary presence, its loamy presence. . . .”

The perspective afforded by German reunification may help make this 672-page journey worthwhile. Or perhaps not, if the reader tires of occasional moments when the author’s German obsession carries his prose away with pent-up metaphorical excesses reminiscent of Thomas Wolfe’s most self-absorbed heroes.

Some might be more put off by the realization that to get to the bottom of this story, one must wade through three more of a planned quartet entitled “To Liskeard,” in which all the characters are headed for a reunion on the Cornish coast. I’m not sure I want to finish the journey, but it is a tribute to the best in this book that I am tempted.

Harrison, the son of actors Rex Harrison and Lili Palmer, has written a dozen stage plays, 60 television scripts and numerous radio dramas. The command of character and dialogue, dramatic twists and a willingness to explore the dark, Dostoevskian side of the human heart show a good playwright’s lineage. But the metaphorical excesses he commits on his first attempt at the broad canvas of the novel could have used more thought and fewer firestorms.