Time travel into the past is tenuous at best as a topic. In this episode a man who has been thinking about the possibility, finds himself at the date and location of the assassination of Abraham Lincoln. He tries everything he can think of in the short time available to him with predictable results. Of course, he is thought to be quite mad. He is arrested and eventually remanded to the very man he is attempting to stop. Serling was bright enough to let him return to the present, but is the present the same? This is kind of a precursor to "The Time Tunnel" where time travelers on a weekly basis were given the same task, overcoming what had already happened. Unfortunately, the implications of the distortion of time and the future always negate the result. Unless you have something like Ray Bradbury's "The Sound of Thunder."