I'm going to be honest, I'm not entirely sure what's exactly going on in this short story. In the story, Kessel introduces us to a nameless* protagonist who, as we quickly find out, not only appears to be immortal, but also totally immoral, travelling across America leaving a trail of senseless murders and various petty crimes in his wake. Furthermore, it appears that he's not the only immortal out there, as he meets a "girl" named Ruth during the course of his story that's also immortal and, like him, pretty randomly psychopathic. To make matters a little more confusing, he might also actually be from the future, and lives in the past because he's afraid of change; of what the world becomes. Of course, that particular revelation comes during a scene in which he's hallucinating from heavy drug use.
So like I said, I don't know what's going on here, but I do know that it's pretty compelling. Despite the central character's psychopathic impulses, the mystery of who or what he is really pulls you along in the story. You really want to know if he's some kind of immortal or demigod or man from the future. Or, if he really is just crazy. Perhaps it's a tribute to Kessel's writing that he doesn't really let us pin the character down into a neat little category. That maybe keeping us guessing is part of the point? Whatever the case, I know that the end result is an awfully good read.
*He might be named "Gerald Spotsworth," or he might be named "Loki." It's hard to tell.