If you're after completing this achievement ASAP, open the spoiler. If you are after enjoying the story without spoiler, just continue playing as you would and this will eventually unlock.
*** Spoiler - click to reveal ***
On your way, the minecart track is broken and you will crash. A Ninja will appear whom you need to fight. After a few evasive moves you get him on the floor and it turns out to be Ivor. You will discuss a lot with him (Choose "Punch him" if you don't want to wait for him to tell a minute long story). Ivor will report back to the admin and you will continue your path.