Hynd, author of murky, dismayingly convoluted spy-thrillers (The Sandier Inquiry, False Flags), offers a much simpler sort of espionage suspense this time--as, with echoes of Eye of the Needle and many other WW II suspense-plots, a super-FBI-man follows the trail of a tricky Nazi spy in 1939 America. Known only as ""Siegfried,"" the undercover, independent Nazi agent has been terribly successful lately: blowing up ships that are carrying arms to Britain, committing ruthless murders as he goes. So J. Edgar Hoover calls on rebellious super-agent Bill Cochrane, the first American to penetrate the Abwehr in Germany, to identify and capture Siegfried--who is now, the reader knows, plotting the assassination of FDR (in order to keep the US out Of the European war). And meanwhile, without explanation, we follow the seemingly unconnected story of Laura Worthington, a spunky Englishwoman who marries young, moody, upper-class American minister Stephen Fowler (who, according to Laura's spy-pals back home, may be some sort of Communist spy). What's the connection between the Siegfried plot and the Laura/Stephen story? Is there, as Cochrane begins to suspect, a mole within the FBI who is feeding secret data to Siegfried? The answers aren't very surprising--though Hynd does make fairly good use of a trick-the-reader gimmick lifted from William Goldman's Marathon Man. And, while Laura (whose husband is Not What He Seems) starts to fall in love with investigator Cochrane, the countdown to FDR-assassination is underway: as usual, no one will believe the hero's direful predictions--so Cochrane himself must rebel against his superiors, joining with some UK spies (Laura's pals) to foil Siegfried's attempt at blowing up the Presidential yacht. Erratically paced, wildly derivative, with four or five borrowed plots jumbled together--but episodic, far-to-middling entertainment for WW II-espionage fans who don't demand fresh twists or distinctive characters.