Take down Decker

Take down Decker is an unmarked quest in Fallout.

Detailed walkthrough
After taking one (or both) of Decker's quests (Dispose of Jain and/or Dispose of merchant), the Vault Dweller can choose to report Decker's crimes to the Hub Police. Sheriff Justin Greene will offer them this unmarked quest if a Charisma check is passed (assuming the Vault Dweller has fulfilled Decker's quests), 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) fast travels to the basement of the Maltese Falcon for an intense confrontation with Decker and his staff.

Rewards

 * 1300 bottle caps
 * +4 Reputation (+1 additional for killing Decker)
 * 1400 XP