Mirror, Mirror

After a storm causes a transporter malfunction, Kirk, Uhura, Scotty, and McCoy are sent to an Enterprise in a parallel, but opposite, universe. They comes to find out that they are serving a new StarFleet which goes against everything their old StarFleet stands for. The ship is filled with brutality, lust, and the drive for power. You can feel the tension as they try to get to their own universe before the rest of the "evil" crew discovers the truth. The only thing that remains constant is a logical Spock, which shows logic stays the same whether good or evil. Also check out Spock sporting a little goatee for this one. The plot idea was a very good concept and it turned out to be one of the better episodes of the second season.