When you enter the route, there is actually an enemy flying so high up, it's off the screen until you jump up to the first ledge. You can safely ignore it, but watch out for the set of heat seeking missiles that are approaching. Eliminate the ones above the ledge, but let the ones below explode on the walls before dropping down to the screen below.
Four heat seeking missiles will approach as soon as you land. Remove them and continue to the right. You'll encounter some small bouncing enemies as you jump up the ledges. One enemy floats left and right at the drop to the platform below. Drop down to the next screen.
You are greeted by one bouncing enemy and two insects that drop down when they reach your location. Clear them and proceed right. Clear out the insect at the top of the ledge, and then drop down to attack the two bouncing enemies. Then drop down to the screen below.
There are no more enemies. Simply walk to the right, and you'll discover a man lying at the bottom of the cliff. It turns out to be Joe. He explains that Guycott knocked him down. Bang asks about the secret of the medallions. Joe explains that they can be used to stop a bomb.
From here, your only option is to go all the way back the way and came and return to the entrance.