MacLean's last novel, Partisans (1983), only made it onto the Times bestseller list for one week, in the #15 slot; loyal readers, perhaps, are coming to realize that the onetime action king is now the king of nonstop talk--padding out thin plots with yards of soporific dialogue. This time the chatting begins when a mysterious terrorist group called F.F.F. blows up a dike, turning Amsterdam's airport into ""an inland sea."" Who are these guerrillas? What do they want? So wonders top-cop Peter Van Effen, who is meanwhile--with unconvincing ease--infiltrating a local terrorist gang, posing (in heavy makeup) as a Polish explosives expert. Could Van Effen's gang (which wants to blow up the Royal Palace cellar) be one and the same with the dikegang? So it seems. And are they also the same gang that has just abducted Van Effen's sister Julie and policewoman/heiress Annemarie Meijer? Yes indeed. But what do they want? Well, eventually it's announced that the terrorists want Holland to pressure Britain into pulling out of Northern Ireland; otherwise, the guerrillas will use missiles and nuclear devices to blow up dikes and flood the entire country. So, after proving himself to the F.F.F. by helping with a Royal Palace bomb, the disguised Van Effen (with two other undercover cops) joins the terrorists at their windmill-hideout; he learns their real motives (a murky, implausible stew); and he manages to foil most of their vile schemes, staying in radio-contact with government forces. Again, the stilted talking never stops--with deadly, repetitive banter. (""My men getting hospitalized, a gang of lunatics threatening to inundate our country, another gang of lunatics wanting to hire me to blow up the palace or whatever, nations toppling, and I'm supposed to be worried about smooches?"") The confused plot is farfetched without being exciting; the pace is ultra-slow--especially in the first half. But things pick up a bit later on--and the dike-bombing notion, if under-developed, may appeal to fans of techno-disaster suspense.