The Spy and the Devil by Tim Willasey-Wilsey

Set in the 1930s, when Britain was trying to appease Hitler, The Spy and the Devil follows Baltic aristocrat-turned-MI6 agent Baron Wilhelm “Bill” de Ropp, who infiltrated Hitler’s inner circle through Nazi ideologue Alfred Rosenberg. Through Rosenberg he met Hitler and became one of the few Westerners with inside access to his court. The author weaves espionage, British foreign policy, MI6’s evolution into a compelling narrative.