You start in a cave. Jump across the gap, and climb up, and you should see two prisoners. You may speak with them to get some background information, but most prisoners just give common messages.
Continue to the right, and climb up. Pick up the two hover bombs, and throw one at the door. WHen you proceed right, you will see your first enemy, a green Grag'ohr. He follows the same tactics as you may seen in practice - he will take cover for a few seconds, during which you should take cover as well. He will pop out to fire between 1 and 4 shots. When you hear him cock his rifle, exit cover and shoot to hurt him. If you did get injured, he will laugh for a few seconds, allowing you to get a free shot against him. Jump across the waterfall, and collect a hover bomb from the enemy before climbing up.
To the left is a solid door. Use a hover bomb to destroy it, and pick up the item on the ground. Get the next hoverbomb, and blow open the second door, and get a heal potion from the prisoner. Climb up, and go through the door.
In the large room, you now need to climb down, and fight the enemy, the same way you did with the first one. He will drop another hover bomb, which you can use to open the door. Continue left, and fight the third Grag'ohr, collect his hover bomb, and enter the final room to the left. Blast open the door, and take the elevator to exit this level.
Note that extra items are not carried over to the next map. While you did have one spare bomb, later levels will give you only an exact number of items required to complete the maze.