Plot.  Another one of the Big 5 (story essentials).   It's the interstate highway of your story, loaded with twists and turns, on-ramps and off-ramps, breakdown lanes, and speed traps.  Plot is one way to drive your story.   ...BUT...

Characters can too.  Best to know what you've got before you start.  Is it a plot driven story or a character driven story?  For now, let's stick with the plot driven variety.

Simply put, a plot driven story is fueled by the events of the story, not the characters.  In fact, the characters are secondary.  The movie Armageddon is a perfect example.  Big rock hurtling towards the Earth...threatening to wipe out mankind.  Yikes.  What shall we do?   The characters certainly have their foibles but top billing goes to the asteroid. Hands down.  Jurassic Park is another good example.  More recently, Pacific Rim.  Plot driven stories make for one exciting thrill ride because the antagonist is, in many cases, other worldly.  Makes a great movie too. 

For more great insight into this topic (and many others), be sure to check out Anita Rogers' blog (writerchick.wordpress.com).