The Night Letter
The Night Letter is a 1978 book by Paul Spike, with a double-layered structure: an anti-Nazi spy thriller on the background of the early part of the Second World War, and an exposure of cynical and machiavellian maneuverings in the American corridors of power.
The book belongs to the subgenre of secret history – i.e. with a plot in which real historical figures play a substantial part, doing things which are the author's invention but which supposedly (for reasons given in the plot) remained secret and did not come to the knowledge of the public.
In the book, a British doctor meets in 1936 with President Franklin D. Roosevelt, who is unaware that the doctor is a Nazi sympathizer. The visitor manages to secretly photograph the President in a compromising position with his secretary, Missy LeHand (whom historians widely assume to have been indeed Roosevelt's mistress).
By 1940, senior Nazi leader Reinhard Heydrich possesses the picture and intends to use the photo for blackmail and prevent Roosevelt from running for a third term – in the hope that whoever gets elected instead would be more likely to keep the US out of the Second World War.
The President must recover the photo before the Democratic Party Convention which is about to nominate him. What makes the situation more difficult is that Roosevelt also needs to bypass the FBI – for apprehension that should the photo fall into the hands of J. Edgar Hoover, the FBI Director might use it for his own brand of blackmail. Instead, Roosevelt employs former FBI Agent Jackson, who had left the Bureau under a cloud and incurred Hoover's personal enmity, and who is completely loyal to the President.
The bulk of the book follows Jackson's chase after the photo, starting from Paris at the very eve of its fall to the Wehrmacht and concluding with a cataclysmic confrontation at a secret Michigan base of the "Silver Shirts" – a murderous, power-mad American Fascist militia (which truly existed, though not necessarily doing all that the book describes it as doing). The chase ends with a mixed result – the Nazi agents have been killed or captured, but the negative did fall into the hands of the FBI who caught the scent of what was going on.
The book ends on a cynical note: Hoover meets the President at the White House, claims to have destroyed the negatives (which is manifestly untrue) and proceeds to imperiously demand the sacking of Jackson – obviously he is under the impression that he now holds Roosevelt's fate in his hand. Upon being shown this, the President presents a photo of his own, showing Hoover in a compromising position with a handsome young FBI agent. Roosevelt and Hoover would henceforth be tied to each other, "like convicts in chain gang", each able to destroy the other but only at the cost of his own destruction.