It's 1944, the Nazis are losing the war. and Heinrich Himmler has decided on one last desperate attempt to save Germany. He makes a decision to send an assassin into the heart of wartime America to kill FDR, with the result that Kurt Monck, a German POW, escapes from a Seattle prison camp with orders to kill the President. Soon after Monck's escape, Secret Service agent John Wren is assigned to the case, and so begins a frantic cross-country chase that ends only seconds away from FDR's death aboard his private railroad car. Filled with brutal competence (he worked for six months behind Allied lines in Africa before his capture), Monck chooses the garrote as his special killing tool, though he can kill in more unorthodox ways as well--one poor soul is blown up with a stomach full of gasoline. Hardly less ruthless than his German adversary, Wren is well versed in murder (having earlier killed his own wife's killer), and at one point coolly stages a mock execution to frighten a suspect into talking about Monck's final destination. In this brightly conceived novel are appearances, too, by a number of historical figures--FDR himself, Treasury Secretary Henry Morgenthau, and J. Edgar Hoover, who drops his wisecracks and for certain moments comes near to taking over center stage. Raising the book above the average of its genre are the historical details the author showers on the reader, from the poignant (a waitress, to make herself more attractive, paints a black line down her calves because she can't get nylon stockings) to the sublimely scandalous (readers get to watch FDR's affair with Lucy Rutherford being conducted in the back seat of the presidential limousine with a Secret Service escort outride) to the wistfully entertaining (a bumper sticker on an old car reads: ""Praise the Lord, I'll soon be ammunition""). With a premise that may be familiar, Thayer's (The Earhart Betrayal, The Stettin Secret) careful research, workable characters, and bright delivery make this one of the best of its kind in quite a while.