To obtain the Lending a Hand side quest in Dead Island 2, approach Luther in his hotel room at the Serling Hotel on Ocean Avenue.
He’ll claim that Denise stole his bag. To begin restoring the peace, speak with Denise guarding the entrance to hear her side of the story. She’ll give you the Waste Disposal Keycard as she threw his stinky bag down the chute. It’s up to you to retrieve it! Drop down to the bottom floor of the hotel then use the keycard to enter the basement.
Search through all the dumpsters then follow the path, opening the gates. You’ll find more dumpsters to search through. These won’t be it either! Use the crates in this room to reach a hole in the wall.
Inside, you’ll find a red stinky bag. Pick it up then bring it all the way back to Luther. Be careful as it will attract zombies!! When you deliver it, you’ll complete the quest. As a reward, you’ll receive 3,000 XP and a Composite Sledgehammer.