Lehman wrote the screenplay for North by Northwest, and you can expect an MGM megaflick of this new something-for-everyone disaster-caper--but it probably won't have Cary Grant, and it definitely won't have the light, smart, suspenseful touch of the Hitchcock classic; here the hand is heavy, and the emphasis is on quantity. No less than 174 amateur hijackers--childless professional couples suffering from cutbacks in the engineering fields--band together, book passage on the luxury liner Marseille, and, blending in with the touristas mid-ocean, quietly and smoothly (well, a few killings) take over the ship, order a changed course, and rig up a sophisticated bomb. In Paris, French Atlantic Line officials get the message: 35 million in gold or bye-bye boat and the 3000 aboard. Radio-less and not knowing which are the 174, weary Capt. Girodt is in a pretty pickle, n'est-ce pas? Mais non! Passenger Billy Berlin, geriatrician and ham-radio nut, has smuggled his transmitter on board, and--egged on by Girodt, the ship's doctor, and horny wife Julie-he secretly establishes contact with the US, seeking retaliation advice and the identity of the desperados. While Julie and equally randy pulp-novelist Harold Columbine flirt with death by investigating on deck, New York, Beverly Hills, Paris, and Washington are hot with suppressed newsbreaks, computerized researching, presidential conferences, and irrelevant bed-hopping. The complex terrestrial doings are dullish, the floating action anything but, what with two lay-and-slay combinations, scores of bodies falling as ""The End"" comes up, and dialogue that's clevercute-awful enough to try reading out loud: ""The way to a woman's heart is through her vaginal itch"" . . . ""You need a bodyguard, and I can't think of a guard I'd rather body."" Occasional moments of appealing characterization and sly-but-believable plot-twisting make one wonder why Lehman felt the need to go for broke, piling everything onto an oceanic oil slick that goes on for miles, reflecting a single word onto the bestseller horizon: gross.