Take down Decker

 is an unmarked quest in Fallout.

Walkthrough
After taking one (or both) of Decker's quests (Dispose of Jain and/or Dispose of merchant, you can choose to report Decker's crimes to the Hub Police. Sheriff Justin Greene will offer you this unmarked quest, promising 300 caps upfront, and 1000 caps upon completion of the quest.

The Vault Dweller's party (now including Sheriff Greene and Deputy Tony Fry) now fast travels to the Basement of the Maltese Falcon for an intense confrontation with Decker and his staff.

Reward
1300 bottle caps and 1400 XP.