From the package of the game:
Something must be done! Another American spaceship has been reported missing. Far too many of our explorers have disappeared near the mysterious Spider City for this to be merely a coincidence. A rescue ship must be dispatched immediately! But who would volunteer for such a mission? Who would have the courage to descent into the tunnels of thet awful city and battle with the wicked Spider Warriors? Who would wish being trapped by a dreadful Disruptor? There is only one person who could measure up for such a challenge - Flash Gordon to the rescue!
You play the role of Flash Gordon. It is up to you to rescue any surviving Spacemen and to conquer this hideous city of tunnels. Spider City is conquered when all of its Hatching Pods are eliminated. It doesn't hurt to blast a few Generators or enemy Patrol Ships while you're there.