The Nazis scheme to hijack the Queen Mary in 1943--en route from UK to US, with Churchill aboard--in a stolid, step-by-step historical thriller that's short on dash and personality. How do the Germans plan to grab the Queen Mary, which has proven U-boat-resistant in the past? Well, first of all (and true to fact), the ship is scheduled to carry a troop of German POWs to America--including the worst troublemakers, like ruthless Major Preuss. Furthermore, the Nazis have managed to slip a secret agent into the Queen Mary's crew: former U-boat officer Ulrich Muller--who survived a shipwreck, exchanged places with a Norwegian sailor, wound up in a Virginia hospital, then trained as a saboteur in Mexico. . . and has joined the Queen Mary crew in N.Y. So, while first-novelist Hughes fills in the events that lead to the POW-transport idea (and to Churchill's decision to visit FDR), agent Muller is sailing from N.Y. to Britain, committing two shipboard murders to preserve his incognito status. But the action only really gets going in the last 100 pages--as the QM sets off from England, POWs and Churchill aboard: Muller makes contact with the POWs; the hijacking is planned (though Preuss is more interested in assassinating Winnie); much violence ensues, with Churchill aide Squadron Leader James Alloway (Hughes' bland quasi-hero) leading the efforts to beat back the Nazi takeover; and, when the hijacking fails, there's a German effort to sink the Queen Mary instead (U-boats have sneakily gathered 'round). . . culminating in some Alloway/ Muller hand-to-hand combat. Decently plotted, reasonably well-textured with WW II detail--but none of the characters comes to life (Alloway's romance with a US journalist is a droopy loose end), the Churchill connection remains dim, and this is a just-passable addition to the crowded WW II/what-if? shelf.