The Breaking Point, by Mary Roberts Rinehart. Part I.

Mary Roberts Rinehart -- "America's Agatha Christie," as she used to be called -- set this story in a New York suburban town, shortly after the end of the first world war. Dick Livingstone is a young, successful doctor, who in the course of events becomes engaged to Elizabeth Wheeler. 

But there is a mystery about his past, and he thinks himself honor-bound to unravel it before giving himself to her in marriage. In particular, a shock of undetermined origin has wiped out his memory prior to roughly the last decade. Rinehart, who presumably had been reading, or reading about, the then popular Sigmund Freud, plays on what today is called "repressed memory," as she takes Dick into his past, and into the dangers that, unknown to him, lurk there. 

Is she correct about the behavior of memory? Who knows? After all, this is not a clinical treatise, but a work of fiction, one of the thrillers that made her such a popular writer of the earlier twentieth century.