Butch Harris of Far Go Traders asks the Vault Dweller to find out why caravans have been disappearing. Harris mentions the deathclaw skeptically, and tells him to go to Beth for more information on it. When talked to about the issue, she directs to Harold in Old Town.
After the conversation with Harold, the Dweller should speak with Slappy outside of Harold's house, who will bring them to the deathclaw's lair.
A problem may arise in the ending of the game which is that while the Vault Dweller may have completed this quest, the ending for the Hub will not be shown and skipped altogether. This is because the ending for the Hub wasn't properly implemented in the game, only an audio file and a picture exist though aren't activated, even if the requirements are met. [verified]
There is another global variable related to the good Hub ending, called KIND_TO_HAROLD and it can be told the specified ending is connected to Harold bringing peace between mutants and humans.
If the Dweller travels to the Military Base, he can then convince Butch that the mutants are responsible for the missing caravans. The quest will be marked as completed, and Butch will direct him to Rutger, but the latter must still be shown the holodisk from the deathclaw's lair. [verified]