You can help Eric Ambler . . . or you can turn the page.

Exactly: It's like one of those charity ads featuring a poster child, bemoaning a disease, and telling you that you can help . . . except what's on view just now is Eric Ambler, the thriller writer. He is leaning against the back of a couch in a hotel lobby. He is being photographed. He's a bit old for a poster child at 72, and hard to feel sorry for, with a string of huge-selling novels stretching back to the biggies just before World War II -- "A Coffin for Dimitrios" (which has never gone out of print), "Journey Into Fear," and so on up through "Judgment on Deltchev" in 1951, "The Light of Day" (which was made into the movie "Topkapi"), and this fall his 20th, "The Care of Time."

Nevertheless: He leans against the back of the couch, enshrined in the anonymity of a blue suit, an off-white shirt of the kind one associates with left-wing Britishers, and a plain blue tie. A Leica whispers at him. He begins to pose. It's a little alarming. He cants his head and seems to push his face forward in the wide-angle menace of a man who is preoccupied, wary, alienated, startled, even quietly and chronically appalled; not at all the face of the deferential old gent who was just moments ago patting companions on the back, urging them through the door you-first, please, all the cultivated hesitations of British middle-class benignity. This is a whole different face, a public face, a perfect spy novelist's face, a face entirely appropriate to this century of sirens clattering off the walls of endless cities; of millenial heavings; of the stateless person whose papers are not quite in order; of an archetypal citizen who is "every country's, every people's bloody foreigner," as he says in the new novel; a face torqued into the subliminal dysplasia of the Balkanized personality; the face of a man who, if he hasn't seen it all, is worried that he will.

Exactly: The Leica whispers its way from frame to frame, and Ambler is turning himself into the poster child for the malaise of the 20th century, right here in the paneled 19th-century snugness of the lobby.

As soon as the photographing stops, Ambler doesn't look like this at all. White-haired and pink-fleshed, he pads happily into the dining room in search of lunch. He has a palate refined by living most of his life abroad -- in Switzerland now, in an apartment overlooking Lake Geneva.

"There's a lot of French talk spoken here, but a lot of it phony," he confides, glancing around the dining room from a corner table. "A waiter said something to me in French, and out of habit, I replied in French. My French is fairly convincing. He immediately switched to Italian." He compresses his lips and flares his eyes with careful delight. He studies the menu.

"I've been eating in California, so I have an appetite. Even when the ingredients are good out there the food is . . . " And his lower lip taps the upper in search of exactly the right word, which doesn't come. "I know a hostess out there who wanted to impress her guests. She told them all, 'I told my cook to gourmet everything.' I hate that -- 'gourmet' as a verb. I'll tell you a couple of other usages I hate: 'if you will,' and 'per se.' People pepper everyday talk with them. 'If you will' -- it's an affectation of academic pride. It's two dogs sniffing each other -- if I give you an if-you-will, you give me a per-se."

He orders a Meursault with his Alaskan king crab Norfolk, talking with the waiter in some sort of French-restaurant pidgin:

"Bon?"

"Bon, yeah," he says, swilling a huge draft of the Meursault over his tongue. "It's good. It is good. Our employers would be pleased to have this on the expense account. They'd wish it."

He smiles mischievously, this man, who, like his heroes, keeps finding himself in the middle of countervailing forces, be they linguistic, financial, or political. And literary: He has spent a life caught between the hopes of his intellect and the vulgarity of the thriller.

"I decided simply because I was an ambitious young writer to have a cause, and my cause became the thriller. I changed it. I was literate and left-wing. The thriller is Kafka country, really, isn't it? Don't think I hadn't read Kafka. I'd read 'The Castle' when I was 15. By the time I was 14 I'd read all the E. Phillips Oppenheim books, Conan Doyle, oh yes, all behind me. I was notorious in public libraries as a child," he says, clasping pink and beautiful hands.

After an education as an electrical engineer, and an attempt at acting, he got a job writing advertising copy, while he wrote novels and plays on the side -- all unpublished. In 1936, he was a hit with "Dark Frontier," which critic Clive James in a 1974 summing-up of Ambler's work described as "engagingly awful." He was launched. He quit the advertising business a year later and went to Paris, where he hung around the literary scene at the Cafe Flore and became, as he told the London Times in 1970, "quite the little intellectual snob."

Now, over the Meursault and the crab Norfolk ("That looks rather good -- not too much of it, though.") he recalls: "I was a kind of radical, I suppose. I saw the thriller as a way of conveying ideas. In 'A Coffin for Dimitrios,' Latimer is contemplating the approach of the 1939 war. He says -- I think I have this right -- 'Men had learned to sniff the heady dream stuff of the soul, and wait while the lathes turned the guns for their destruction.' I stole the phrase 'heady dream stuff of the soul' from Spengler's 'Decline of the West.' "

As Ambler was growing up in London in the '20s, the thriller was stuck in a mold of bully-boy jingoism. "It came out of the Anglo-German rivalry of World War I -- I don't include James Fenimore Cooper's 'The Spy' as an example of a thriller. There were the Black Gang books of the mid-'20s with Bulldog Drummond and his friends dressing up in black shirts and flogging Jews and Communists."

Ambler set out to change all that, inventing a popular novel described in the Manchester Guardian in 1972: "Someone, usually a man of inconspicuous appearance and accomplishments, will have left his normal surroundings to go to a strange place. There he will have been drawn by circumstances and his own foolishness into events of an outlandish nature, from which he will find it impossible to extricate himself . . . The villain will be as colorful as the hero is colorless, he will be gross and excessive, with extreme appetites of one sort or another, while the hero or narrator will tend to be abstemious, reserved, unused to firearms or women, physically weak, but possessing a native shrewdness, and some special knowledge that in the end turns the tables on his more powerful adversary."

"They're all me, all my heroes," says Ambler, happily clasping his hands over the empty crab dish. "I pulled a joke on a woman on television. I said: 'Didn't you find the character odious?' She said: 'Yes.' I said: 'It's autobiographical.' "

They are works of "imagination but not fantasy," he says. He differentiates himself from the "realist" school of thriller writing exemplified, he says, by John le Carre'. His books are works of gritty, understated atmosphere and technological expertise. They illuminate a world of shifting identities fixed only temporarily by passports and noms de guerre. They are existential -- his characters get involved in lethal intrigues for no good reason. "The warning message arrived on Monday, the bomb itself on Wednesday. It became a busy week," he writes to begin "The Care of Time." The chapter endings are haikus to the age of anxiety: "What I found in my sitting room instead was a fog of panatela smoke and a delegation of three." Or: "Then he coughed once, tried to swallow, and suddenly went into a paroxysm of laughter."

He is a writer of thrillers, not mysteries, he insists. Nevertheless he has won the Edgar Allan Poe award, and the Grand Master Award of the Mystery Writers of America.

In the paneled dining room, with the small and timeless glamor of a single rose or bird of paradise on every table, a beeper keeps going off -- a telephone? An alarm? Just another 20th-century disjuncture?

"My stories are about loss of innocence," he says.

In 1940, he was commissioned in the Royal Artillery, and saw combat in Italy. Later he worked with a film unit, turning out educational and training films. He stayed in the movies after the war, and lived for years in Hollywood, writing movies such as "The Cruel Sea," and "A Night to Remember." He spent one year earning $6,000 a week writing 14 drafts of "Mutiny on the Bounty," none of which pleased Marlon Brando, who later would doom the movie with his portrayal of Fletcher Christian. "He was courteous," Ambler says. "Courteous but silly." He left the movies in the '60s -- "You outgrow the movies, unless you're a director" -- and kept writing novels, and getting rich. But not acquiring a taste for conservatism.

"It's so easy -- the quondam socialist grows rich, and suddenly finds salvation in the board rooms of the Common Market. I find myself saying: The issue is social justice. Social justice is something going largely by the board at the moment. I remember my own childhood, and how it was to be, not poor, but hard up -- do you have that expression in America? In my school, half the children had no shoes. High conservative administrations are cruel to people who can't defend themselves."

He keeps writing, despite the arthritis that has numbed his fingers. "In the 16th century they called it scrivener's palsy. It affects vertebrae at the top of the spine. I'm in remission right now -- that's what we arthritis buffs call it. I used to write everything by hand but I had to learn how to type. I do so many drafts. I start with a sort of minimum idea, just a scene will do, and I build from there. For instance, we live on this lake in Switzerland he and his second wife -- he has no children . The lake has one of these little small-boat harbors which is infested on weekends. Opposite that is a small island. There is a house on it. I've never seen anybody in the house. It is rumored to have rats. One rainy day in the middle of the week a limousine pulled up to the dock. A chauffeur got out, wearing leggings. Then a tall thin man got out and waited while the chauffeur lugged out a rowboat and brought it around. The master got in. He stood up -- he didn't sit down on the wet seats. This was very interesting. The chauffeur rowed him out to this island in this small dinghy."

His hands, which have been moving closer to each other, spring apart.

"The image remains," he says. "I began to wonder about it. It was the relationship between the master and the chauffeur that interested me. What nationality is the master? I shouldn't have found out but I did -- he was a post office inspector from Zurich. I lost interest."

How very 20th century, with all that ambiance of rain-shrouded decay, despair, drudgery, displaced persons . . .

But Ambler is not the adventurer who comes to mind when we think of that uniquely 20th-century man, the thriller writer. Instead, he describes himself as: "Timid. Yes, timid. Though I suppose the American image of 'timid' is something different from what I mean. In America, the image of 'timid' is Caspar Milquetoast. I'm not Caspar Milquetoast. I'm really a rather nasty fellow. I was a colonel in the British army. I remember in unarmed combat training, they taught us that if someone pushes you in the chest, you pull his arm toward you by the elbow and break his wrist. Someone pushes you and you break his wrist -- it seems appropriate, symbolically."

It's strange -- here comes that face again -- the canted glare of the 20th-century poster child, swollen with paradox and gleaming across the table and his glass of Meursault.

"Of course, I have to watch the silly-old-f--t syndrome, it's easy to slip into. I'm very frail. You don't think I'm frail?"

He seems to be using that frailty as a threat. His face -- lips stretched thin, eye-flesh rigid -- could belong to either the secret police officer who pounds on the door in the middle of the night, or to the man answering; Ambler being, of course, the man in the middle, like both his heroes and his readers.