The Legend of the Star

 is a quest in Fallout: New Vegas.

Quick walkthrough
Collect 50 Sarsaparilla Star Caps and deposit them in the machine in Sasparilla HQ.

Once you collect enough, another collector will come to assassinate you. You can kill him and take his 8 star caps.

Detailed walkthrough
In order to complete this quest you need to find 50 Sunset Sarsaprilla Blue-star Caps and return them to Festus. Festus is located inside the Sunset Sarsaprilla headquarters, which is south of The Thorn and east of Jacobstown. Upon completing or failing this quest it unlocks another quest.