The Mysterious Venture quest is a quest in which the player must find and collect various bombs for Marlon(30 cherry bombs, 20 bombs, 10 mega bombs), the quest-giver. The quest can happen at any time of year, but the player only has a limited time to complete it.
Once you have collected all of the bombs for Marlon, you need to bring them back to Marlon’Chest. He will reward the player with 8000 gold for their efforts, and the quest is complete.
Marlon’s Chest: Where to find it
The chest is located inside Marlon’s house, at the back.