In this story, the sniper must trick his enemy so that he can safely exit the roof of the building. Remember that he is injured because the enemy has shot him in the forearm, and he has only a revolver to help him escape.
The sniper, therefore, develops a plan. First of all, he removes his cap and places it over the end of his rifle to make it look like the silhouette of a man. He then raises the rifle so that the enemy can see it. The enemy, believing that the rifle is the sniper, fires and hits the cap. To make this ruse look authentic, the sniper allows the rifle and cap to slowly fall to the ground.
The enemy now believes that he has killed the sniper, and he moves out of the darkness and between two chimney pots. The sniper now takes aim with his revolver and shoots at the enemy. His shot is successful; the enemy is killed and falls to the ground below, enabling the sniper to escape.