Engima, despite its name, is actually a quest. This quest is given by the Mysterious Warrior in Iron Mountain Highway. This quest is given after completing the Moonflower quest. You are required to give Mayor Bumbee the Moonflower you retrieved from the previous quest.
Quote from the Mysterious Warrior:
"Alright. Now return to Crossroads and deliver that Moonflower to the Mayor. She'll understand the message behind it and she needs your help. See ya around, kid."