K.C. Lee, or Casey, as he is called, is the protagonist of the first Mr. Moto book, No Hero. Mr. Moto himself is a Japanese enemy agent, albeit someone of honor, wisdom but murderous efficiency, too.
Set in the early 1930s, No Hero perfectly captures the mood of the times. The rising power of Japan, the naval arms race in the Pacific, and the dismemberment of China all play thematically in Marquand's look at the Orient. And it should be the "Orient," here, not "Asia." Culturally, the Orient of the 1930s signified unknowable peoples and cultures, alien values, and a decadent disregard for life. Race is an acknowledged ideal of the book. No Hero plays up to these motifs and ideals but incorporates them into a convincing "hardboiled" detective story. It should be pointed out that Casey is no detective, not even a spy as are all the other main characters in this novel, but an aviator down on his luck, an adventurer looking for someone to finance his next journey. It is this that entraps him into the ring of spies he must deal with.
And there is a love interest, an effective femme fatale, Sonya. All plays out in the expected fashion of the genre. But it does so against the grand sweep of the Orient--Tokyo, Yokohama, Shanghai, and the Chinese interior. The setting of 1930s Shanghai has now become iconic. But when Marquand was writing this novel, he was one of those helping to establish and define the iconography of the "Mysterious East."