From The Vault
The NCR crime boss, Merk, looks to secure some valuable propert - information, in this case, data on Enclave cyberdogs. After killing the Enlightened One in downtown NCR, the Chosen One gets a single opportunity to ask for more work and will be sent to Dr Henry to retrieve the papers. It's easy enough, just barge into the clinic and snatch the papers from his desk.
However, if you killed Dr Henry (for any reason), you will be attacked by Merk (unless you have CH 9, then you can pay 500$ to let you go).