To the Mattresses

 is a quest in Fallout 4. After completing the quest The Nuclear Option, the Sole Survivor should speak with Desdemona. She will tell the Sole Survivor that now The Institute is no longer a threat, the L&L Gang is the greatest threat to The Railroad. She will assign the Wanderer to eliminate one of the Gang Bosses.

Quick walkthrough
1. Kill (L&L Gang Boss)

2. Report back to Desdemona

Detailed walkthrough
1. Kill (L&L Gang Boss)

Travel to the location that Desdemona specified on your Pip-Boy and kill the L&L Gang Boss. They will all be named enemies.

2. Report back to Desdemona

Go back to the Railroad HQ and talk to Desdemona. She will reward you will bottlecaps and sometimes a random item. Check back with her periodically and she will give you the quest again five more times and reward you better on the sixth and final completion of the quest.