Andy and Charlie

Andy and Charlie is an unmarked quest

Detailed walkthrough
Former NCR Ranger Andy will ask the Courier to check on Ranger Station Charlie. Upon arrival, it becomes apparent that all the rangers have been wiped out by Caesar's Legion, who left behind two holotapes. The first is located under the desk and the second one is on top of a metal box next to the same desk.

The first holotape is an abortive log recording by an unsuspecting ranger just before the attack. The second holotape is a recording of a legionary boasting that by wiping out the base, they are sending a message to the NCR. The legionary also states that they took a female ranger captive.

Returning to Andy allows the Courier to inform him of the Legion attack. By passing a Speech check of 60, they will lie to Andy, claiming the attackers were also killed and were unidentifiable. Either way, the player character will net 100 caps, reputation with both the NCR and Novac, and Andy will teach them a special unarmed move, Ranger Takedown.

If the Courier has previously spoken to Andy about his broken leg and passed a Speech check of 30, he will teach them the Ranger Takedown without the player character needing to complete the quest. Following this, informing Andy of the attack will cause him to give them 200 caps, rather than the usual reward of 100 caps and the unarmed lesson.

Bugs

 * After speaking with Andy and traveling to Ranger Station Charlie, one may find no rangers outside, but once inside the station, the only living person will be Comm Officer Stepinac, causing no holotapes to spawn and rendering the quest impossible to complete. This happens when starting the Return to Sender Quest after this one, since this quest requires the Courier to deliver the new codes to Stepinac.
 * Sometimes, while listening to holotape 2 and stopping the recording before it finishes or vice versa with holotape 1 can cause the quest to be impossible to complete. When asked what was found at the station, the option to inform Andy that the ranger base was attacked by the Legion will not be present. One will only be able to say that they found bodies but no evidence as to who killed them, thus, no completion of the quest.
 * This can be fixed by interacting with the radio on top of the desk where the holotapes are found.
 * Even if this quest is not active, people may sometimes say, "I heard there was a massacre at one of the ranger stations, not sure which one though." Although nothing has happened there yet.
 * It is possible to learn the Ranger Takedown move twice by completing this quest and by passing the Speech check.
 * To get the quest, after offering to check the outpost, choose "Goodbye" and Andy should ask to check the outpost.