FICTION

Summertime , by Maureen McCoy (Washington Square, $6.95). This second novel by the author of Walking After Midnight opens with the elopment and marriage of two octogenarians, Jessamine Morrow and Hazen Batten. Though Jessamine knows just what she's doing, the marriage is almost more than her daughter-in-law, Alice, can handle. Widowed, Alice has come to lead a life apart from others. Her daughter, Carla, can't seem to settle down with her husband. But Jessamine's marriage means that the three women will come together over the course of a summer, renewing their relationship with each other and discovering things they thought they had forgotten about themselves.

Replay , by Ken Grimwood (Berkley, $ 3/4.95). This novel is based on a premise most of us have probably entertained: What if we could live our lives over, knowing what we know now? At 43, Jeff Winston, a radio station news director, has a heart attack. In his last seconds of consciousness, he realizes he is dying, but he is surprised to find himself alive in 1963, a student at Emory University in Atlanta, 18 years old and knowing everything important that will happen for the next 20 years. Winston uses his knowledge to become rich, but at age 43 in his new life he dies, and again returns to consciousness, knowing he will have to live his life over and over again.

Loving Little Egypt , by Thomas McMahon (Penguin, $6.95). This is the story of Mourly Vold, nearly blind and a prodigy at physics, who in the 1920s discovers how to tap into long distance telephone lines and sets up a network for others like himself. It features such real people as newspaper czar William Randolph Hearst and Alexander Graham Bell (who delights in Vold's exploits). In a brief note at the beginning, the author acknowledges the influence of the "phone phreaks" of the 1960s and 1970s -- merry pranksters who infiltrated telephone lines with homemade electronic devices, not just to make free telephone calls, but because they were intrigued with the technology and the notion of being able to talk to anyone anywhere at any time.

NONFICTION

The Fitzgeralds and the Kennedys , by Doris Kearns Goodwin (St. Martin's, $5.95). Talk about a dynasty! Beginning in 1863 with the baptism of a boy baby born into the poverty of Boston's immigrant North End, this story of two families gradually achieves the level of classical drama as exhilarating family triumphs alternate with terrible family tragedies. Widely praised for its firm yet compassionate approach and based on meticulous research, this is at once a work of first-rate popular history and a masterpiece of storytelling.

Jesse Owens: An American Life , by William J. Baker (Free Press, $9.95). Jesse Owens' achievement in the 1936 Olympics in Berlin is all the more amazing when one considers the circumstances under which he won four gold medals. It is not simply that the Nazis considered him a member of an inferior race, but the conditions under which he competed: The cinder track at Berlin Stadium was wet because it had rained throughout the day. Both the track and the path to the long-jump pit were rough and uneven. Owens' shoes, heavy compared to today's synthetic fabric footwear, absorbed water, becoming heavier still. Nonetheless, Owens won four gold medals -- in the 100- and 200-meter races, the long jump and the 400-meter relay. This is the story of Owens' life, from his birth in Oakville, Tenn., in 1913 to his death in 1980.

Kit Carson: A Pattern for Heroes , by Thelma S. Guild and Harvey L. Carter (University of Nebraska Press, $9.95). Kit Carson -- mountain man, scout, soldier and Indian agent -- was as authentic an American hero as ever lived. He guided Fremont's expeditions through the Rockies, the Great Basin and California, helped establish the California republic at the outset of the Mexican war, and subdued hostile Apache and Navaho tribes in New Mexico Territory. Later, in dime novels, his life became the stuff of legend. This scholarly work is the definitive biography; it seems the historical Kit Carson was every bit as colorful as the mythic one. Said contemporaries: Kit Carson "wasn't afraid of hell or high water"; his "word was as sure as the sun comin' up," and he "never cussed more'n was necessary."

The Deal of the Century: The Breakup of AT&T , by Steve Coll (Touchstone/Simon and Schuster, $8.95). When MCI won its antitrust suit against AT&T in 1984, the Bell System was broken up. Government officials and politicians, not to mention consumers, are still assessing the fallout. Here is the dramatic story of Ma Bell's demise, vividly told by a financial reporter for The Washington Post.

Billy Wilder in Hollywood , by Maurice Zolotow (Limelight Editions, $12.95). Screenwriter and director Billy Wilder has been one of the most successful artists ever to relocate from Europe to America. (Born in what is now Poland, he decided to leave Germany, where his career began, when Hitler became chancellor.) Landing in Hollywood, he wrote screenplays for Lubitsch (Ninotchka) and Hawks (Ball of Fire) before becoming a director in his own right. His works include films noirs and screwball comedies, at least four of which are masterpieces: Double Indemnity, Sunset Boulevard, Some Like It Hot and The Apartment. First published in 1977, this is an updated account of a resilient career. Among its revelations is that Gloria Swanson was his third choice for the role of Norma Desmond in Sunset Boulevard, after Mae West and Mary Pickford.

Playing God in Yellowstone , by Alston Chase (Harvest, $10.95). Using Yellowstone, the world's first national park, as his example, Alston Chase argues that lack of a coherent managerial philosophy leaves the park system vulnerable to commercial incursions and biological anomalies. "Indeed," he writes, "the park's reputation as a great game sanctuary is perhaps the best-sustained myth in American conservation history." Whether or not one agrees with his explanation, there is no denying that much of the wealth and diversity of Yellowstone's wildlife has been lost in this century, long after it had been set aside for special federal protection.

MYSTERIES The Traveller , by John Katzenbach (Ballantine, $4.95). A serial killer has decided to go back to the scenes of his past crimes (at the same time committing a few more for old times' sake). To make his trip especially memorable, he kidnaps a young woman, forcing her to travel with him and to record his bloody business. In hot pursuit is Mercedes Barren, police detective, who has a special reason for wanting to find the killer -- her niece was one of his victims. And then there is Martin Jeffers, a psychiatrist who specializes in the treatment of sex offenders. Jeffers, too, is trying to track down the killer, and for a special reason -- the killer is his brother.

The Digger's Game , by George V. Higgins (Penguin, $3.95). The author's first book, The Friends of Eddie Coyle, was a tough act to follow, but he followed it handsomely with The Digger's Game, his second. The story is told largely in dialogue and by indirection; the reader who doesn't pay attention will soon lose the thread of plot. In this case that thread involves a barkeeper, Jerry Doherty, who supplements his legitimate income with illegitimate capers on the side. One thing leads unhappily to another and before long Doherty, the Digger, finds himself in hock to an unpleasant gambler to the tune of $18,000. Higgins stages amusing scenes, sketches entirely believable characters and constructs a taut, lively story.