By Ian McEwan

Doubleday. 270 pp. $18.95

BERLIN is the phoenix of world cities. It has gone up in flame (literally and figuratively) so many times, yet continues to have both the magical and ominous ability to return to life again and again. An actress friend who lives there said of recent events "What other city could go to bed one night with two million inhabitants, wake up the next morning with four, but not go nuts?"

How has it withstood all these earthquakes? Because it has learned, by necessity, to be a survivor in the fullest sense of the word; a scrounger in the ruins of what was. Visit other great cities today and the difference is apparent almost immediately. London still refuses to accept change (and the reality of the latter part of the 20th century). Consequently, it reminds you of a great warrior who, stunned or wounded in battle, refuses to retreat or change its original tactics. New York, on the other hand, is in full retreat, screaming "Every man for himself!" and ignoring whatever wounded lie by the road.

Berlin is cagey and smart. It knows when to duck, it knows when to pop its head up to have a look around. It might even be the ultimate city of the future because, having been bent and twisted in so many different ways, it is now the most supple of all. A gymnast of cities, as well as phoenix.

Ian McEwan's latest novel, The Innocent, is set in the Berlin of the mid-1950s. Leonard Marnham, a rather bland and naive British post office technician, is sent to the city to help work on a secret tunnel that is being dug by the Americans for the purpose of tapping the direct telephone link between East Berlin and Moscow. Almost as soon as he arrives, Marnham meets Maria Eckdorf, a German woman both beautiful and enigmatic. Like the city that is her home, Maria is a survivor but no innocent, having undergone experiences both in the war and afterwards that would have destroyed a lesser being. The story of their courtship and the marvelously evocative descriptions of the city are the strongest parts of the novel. At its best, The Innocent has the spooky, crooked-angled, danger-around-every-corner feeling of a Carol Reed film. It reminded me often of The Third Man and that is no mean feat.

McEwan made his reputation some years ago writing aggressive, shocking short stories that left the reader stunned, even disgusted. For the first half of this novel he seemed to be going in a different, less dramatic but more interesting direction. Paralleling Leonard and Maria's love affair with Marnham's increasingly more dangerous surveillance work, the author successfully and often beautifully blends the two disparate stories. "Their hands fitted well, the grip was intricate, unbreakable, there were so many points of contact. In this poor light, and without his glasses, he could not see which fingers were his own. Sitting in the darkening, chilly room in his raincoat, holding on to her hand, he felt he was throwing away his life. The abandonment was delicious."

Yet throughout, one gets the feeling something more must happen to this man, something huge and probably disturbing that will both end Marnham's innocence and change his life irrevocably. When it does, the event is more ghastly than unexpected. The "old" Ian McEwan is at work here and the result is unfortunately more melodramatic than compelling.

Certainly grand guignol endings can be an effective means of ferrying characters from one shore of their lives to the other. But here the horror is so awful and described in such gruesome, coldly excessive terms that whatever beauty and subtlety existed in the story up to that point is largely lost. In the moments after a flashbulb pops in our face, it's impossible to see anything but that silver burn of light. By the time the reader's vision returns in The Innocent, the story is drawing to a close. What happens to the characters is, although cunning and unforeseen, not as satisfying as you'd like.

Jonathan Carroll, a novelist who lives in Vienna, is the author, most recently, of "Sleeping in Flame" and the forthcoming "A Child Across the Sky."