LOVING ROGER By Tim Parks Grove. 151 pp. $15.95

Tim Parks' excellent first novel "Tongues of Flame" was among many other things a story of obsession: a community's fixation on a charismatic minister, who ultimately reveals himself to be the Devil incarnate. Now, in the even more accomplished "Loving Roger," Parks turns once again to the same subject, but with twists so unlikely and unexpected as to provoke as much surprise as delight; in every respect "Loving Roger" is a bravura performance, one that clearly establishes Parks, who is in his early thirties, as among his generation's most gifted writers.

The narrator of the novel is a young woman named Anna, a typist at a London firm called PP whose business has something to do with printing. She is a pleasant but ordinary person, who lives with her mother and father and escapes into the television set or romance novels. Then PP hires a new typesetting salesman named Roger, and Anna's life completely changes. To her he seems the embodiment of sophistication, ambition and good looks:

"He was handsome and intelligent and he had interesting ambitions and I thought with a man like that I could feel proud and in some way I would have slipped out of the mainstream that took you to where my parents were, bricked up with their glass ornaments and the television like buried pharaohs ready for their journey into the next world. But then the other thing maybe was this great capacity to love I feel, this tremendous sense of warmth that smothers me sometimes, that makes me want to cry; and I did feel this warmth toward Roger with his nervous gestures, his sense of being trapped in a job he didn't want to do, his desire to make it, not to let life slip through his fingers, the intensity he had when he talked to me from glowing eyes and said things I didn't always quite understand."

Anna falls quite madly in love with Roger: "I loved him dearly, I really did. I loved his hair and his eyes and his face and the way he was made. I loved the way he pushed his hand into his hair. And I wanted to go on loving him, because it would be so hard to stop." She moves into a place of her own and the two become lovers, though Roger never completely moves in with her and always keeps his options open. For all his good looks and his style and his literary ambitions, he is a child at heart, incapable of making firm and lasting commitments, a spoiled brat who "didn't want life to be real until he decided so."

So gradually it dawns on Anna that she has gotten both more and less than she had bargained for: more difficulty, less love. She becomes pregnant and gives birth to Roger's son, but not even this forces him out of his vacillation. She is upset and fearful, yet she loves Roger so desperately, so blindly, that she cannot take decisive action. She knows she should tell him, "Now leave me or do what the hell you want to do, but at least face up to life as it is," but she is too afraid of the consequences. Eventually, though, it becomes obvious that this obsessive love has drawn Anna into a situation from which she can expect nothing but grief:

"I thought about the two sides to his character, the one that exploded at me and the one that exploded at himself; and I thought about my own character, the way the more he was a bastard the more I somehow wanted to mother him, even though I felt like screaming too -- I tried to think all this over clearly and make some sense out of it, but I couldn't fathom it at all. Only you could see we might both end up in a home if it went on much longer like this."

It doesn't, because at last Anna forces herself to action. What she does is both drastic and terrible, but Parks gives it a final twist that ends the story on a surprisingly amusing note -- a twist such as is to be found in the macabre short stories of Roald Dahl. And even after she has done it, Anna finds herself saying, "Oh Roger, I love you, you know I do."

It is a small, quiet story, out of which Parks wrings every ounce of drama and humor precisely because he resists every temptation to inflate. With the exception of a few passages told in Roger's voice, we are kept entirely within Anna's mind and experience, both of which prove rather more capacious than first impressions led us to expect.

It is indeed the character of Anna that is Parks' finest achievement in "Loving Roger"; he accepts her on her own modest terms, takes a wry if sympathetic view of her various limitations and, ultimately, reveals her to be every bit as resourceful as her situation demands. In one respect, though, he cannot help her: Right to the end, Anna loves Roger.