In the main, Alistair MacLean has built his reputation on being a good spinner of tall tales -- and of writing better than most in this genre. But usually, no matter how packed with incident- yes and coincidence -- his adventure tales have been, somehow he has made them plausible, with carefully developed atmosphere, background of factual data, and a convincing thread of story and character. This time, however, he takes his readers outside the boundaries. It would be very hard to credit this story of a piracy at sea, even after the true tale of the Santa Maria hi-jacking. For here virtually a whole crew is smuggled on board a luxury freighter, coffins conceal atomic weapons, a project is thought out to the final point of taking over still another ship and securing a vast fortune in gold. And everyone seems to achieve the impossible. The hero, a First Officer, bucks stormy seas, held in the waves by a slender nylon rope- and this despite serious head and neck injuries and a badly damaged thigh. Men are killed- and disappear overboard. And the rendezvous is plotted and planned and executed, only to be foiled at the last moment. This time MacLean stretches the credulities too far.