Picking Up the Trail

 is a Fallout 3 quest. It is also an Xbox 360 and PC achievement. It is achieved upon arriving at Vault 87. There are two ways to enter Vault 87:
 * 1) Surviving Murder Pass, you must speak with the Mayor or Princess to get the gate to Murder Pass open.
 * 2) Learning that there is a door that won't open from the Mayor, speaking to Joseph, and then hacking the terminal (average difficulty) to open the back door into Vault 87.