The storyline for "The Alternative Factor" is a great concept  the possibility of a negative parallel universe and a madman whose insane actions could lead to the destruction of EVERYTHING. But there are several aspects of this episode that really bother me, and IMHO, "The Alternative Factor" is the worst first-season episode. <br /><br />I like the concept for this episode. I also like the dialogue between Kirk and Spock in the briefing room when they finally put all of the pieces of the puzzle together. But letting Lazarus roam freely about the ship is a flaw I can't excuse, and the final solution seems a bit drastic. I'm also not a fan of the special effects. For the most part, first-season episodes are pretty good, but this episode feels like it was put together in a big hurry. I'm giving "The Alternative Factor" a D grade and will find an alternative episode to watch when I can.