Words on the Wall

Exploration Stage: Post Office
From: Mr. Black
Description: To storm the Security Service's temporary headquarters at the Post Office, the criminals must have a very significanst motive. We need to discover it! For starters, let's determine what kind of gang it is. Help me find their tracks, you're a pro at this.
Completed: It's not exactly what I was counting on, but this graffiti was definitely left by the attackers - impudent fools who want me to get out. We've been visited by the Resistance!