Papers on Metapsychology is a collection of essays by Sigmund Freud, the preeminent psychologist of the twentieth century. In his essays Freud lays out a speculative set of neurological functions that he believes explain the workings of human psychological behavior. Freud's theories are far-ranging and varied, purporting to plumb the depths of the darkest human impulses. The works spend large amounts of time investigating possible neurological roots for deviant sexual behavior, violence deviancy, and other psychological abnormalities.
This is a good choice if you're looking for a quick read or refresher rather than an in-depth analysis. You'll get a brief book summary and chapter by chapter breakdown. The website loads quickly with minimal advertising.