For mystery readers, every book is a beach book and every day is a beach day. But even genre novels present a variety of escapist choices. I don't know about you, but mysteries that make me laugh go right into the book bag. And Deborah Coonts makes the cut with WANNA GET LUCKY? (Forge/ Tom Doherty, $24.99), set at the Babylon Hotel, "the newest, most over-the-top megacasino/resort on the Las Vegas Strip." The story opens with the gaudy death of a woman who falls out of one of the hotel's private helicopters, landing in the lagoon in front of the Treasure Island Hotel and "disrupting the 8:30 p.m. pirate show." But not even death-by-helicopter-drop can compete with the porn industry's Sex-a-Rama fair or the swinging Trendmakers party, with music provided by the Naked Mariachis. Lucky O'Toole, the statuesque beauty in charge of customer relations for the Babylon, narrates the novel in a voice that aims for brittle sophistication but melts into girlish gush whenever she's in the company of the sexy men in competition for her heart (and other body parts). No matter. Lucky has some nice things going for her, including a mother who operates Mona's Place, held in high regard as "the best whorehouse in Nevada." Blessed with the insight to find humor in the human condition, Lucky can also deal with 400-pound men of the cloth who pass out without benefit of cloth in a public stairway. Let's just hope the job doesn't wear her out. Tarquin Hall writes amusing mysteries set in Delhi and featuring Vish Puri, the conscientious proprietor of Most Private Investigators Ltd., a firm specializing in "matrimonial investigations." Meeting Puri again in THE CASE OF THE MAN WHO DIED LAUGHING (Simon & Schuster, $24), it's reassuring to note that he isn't at all fazed when the Hindu goddess Kali materializes at a Laughing Club held in a public park, smiting down Dr. Suresh Jha, a noted atheist and "Guru Buster." Hall's affectionate humor is embedded with barbs. Puri is sympathetic to Dr. Jha's view that as long as "corruption ate at the heart of the political system" India would never cast off its feudal yoke. So even as this amiably fatalistic detective tries to explain the rules of bribery to a client ("Sir, in India the line between what is legal and what is not is often somewhat of a fuzz"), he feels honorbound to solve Dr. Jha's murder. The humor is decidedly morbid in Sophie Littlefield's down-home mysteries about a female vigilante who extends a helping (if occasionally bloody) hand to battered women in rural Missouri. Stella Hardesty, who owns a sewing machine repair and supply shop that she inherited from her late husband, doesn't look dangerous, although everyone in town knows about the wrench she was clutching when the sheriff discovered her husband's body. In A BAD DAY FOR PRETTY (Thomas Dunne /Minotaur, $24.99), Stella is itching to get on with her re-education of the "no-good, wife-smacking, covenant-breaking" men of Sawyer County. But first she has to keep one of her successfully reclaimed subjects from being locked up for the murder of an unknown woman whose mummified body surfaces when a tornado rips through the fairgrounds. And just when another tornado is heading for town. Jack Reacher, the protagonist of Lee Child's pumped-up thrillers, was born without a funnybone, but he's indisputably the best escape artist in this escapist genre. In 61 HOURS (Delacorte, $28), Child drops a few more hints about the shadowy past of his hero, an ex-military cop who lives on the road, carrying no bags, traveling by instinct and stopping by chance. Reacher is hitching a ride on a church-group tour bus when a blizzard blows him into a small prison town in South Dakota. Forced to sit tight for a few days, he finds himself minding an interesting older woman marked for elimination because she witnessed a crime. The encounter gives Reacher a chance to talk more than he usually does, but it doesn't slow him down a bit. In her lighthearted way, Elaine Viets applies Child's inspired formula to her "dead-end job" mystery series featuring Helen Hawthorne, who left home when a heartless judge in St. Louis awarded her no-good husband half her future earnings. Helen took to the road, living cheap, moving often and working in places like Snapdragon's Second Thoughts, the Fort Lauderdale consignment shop where we find her in HALF-PRICE HOMICIDE (Obsidian, $22.95). Nine books into the series, Viets is still working clever variations on the theme of an emancipated woman making the most of her limited options. To fulfill the genre conventions, a real-estate developer's trophy wife is murdered in a dressing room. The real draw, though, is Viets's snappy critique of South Florida, especially her acid-etched sketches of the shop's clientele. If all good mysteries make ideal summer reading, what does a mystery fan turn to for true escape? How about a supernatural mystery that intensifies the suspense by thickening the atmosphere. SO COLD THE RIVER (Little, Brown, $24.99), by Michael Koryta, is a superior specimen, with its eerie tale of a lovely valley in Indiana where at one time an elixir known as Pluto Water bubbled up from the underground springs. The restoration of the valley's two old spa hotels attracts the interest of a cinematographer from Chicago who drinks the water and starts having visions. The scary parts aren't all that scary, but Koryta sets a beautiful scene, resplendent with dreamy images of phantom railroad trains and ghosts who wear bowler hats and play the violin. If all good mysteries make ideal summer reading, what does a mystery fan turn to for true escape?