Discribe your favorite Star Trek episodes from any series. Here's some off the top of my head.
The Best of Both Worlds: Were the Borg attack the Federation and capture and assimialte Captain Picard. The only way they believe they can stop the Borg is to fire a burst of energy through the main deflector dish which would destroy both the Borg and the Enterprise. And at the end of part part one Ryker give the order to fire while Picard is still on board the Borg ship. This by far is the mother of all cliff hangers.
Another one is when Captain Jellico takes command of the Enterprise while Picard is sent on a special assignment. While Jellico's command style rubs everyone the wrong way, in the end he gets the job done and rescues Picard from the Cardasians.