You are Garret, the master thief who is rarely seen and never caught. In order to prevent the arrival of the Dark Ages, you must steal the city's oldest treasures.
The path to these treasures requires you to sneak past guards, pick locks, and break into secure residences. It's best to avoid the armed guards, hired muscle, angry thugs, and hideous monsters that populate the streets.
You'll have plenty of thief tools to help you slip through the shadows; in case that doesn't work, you'll have plenty of weapons to defend yourself.