You can then quick-travel to locations as near to each designated spot on the map, and approach each guard. The idea is to activate this side quest as your active quest on your Pip-Boy (if you haven't done so already), which will show the three scouts' locations on your map.
We won't spend too much time explaining how to find these scouts and acquire their documents, because doing so is actually rather easy. This time, he wants you to go ahead and visit with three separate scouts in the field, in order to collect their reports, which will then be brought back to McNamara to continue to the next leg of this very lengthy side quest. Unfortunately for you, however, McNamara really trusts you now, and has more obnoxious tasks for you to undertake. Even if you're following our walkthrough, this action is mandatory, and won't mess with the outcome you're going for. Meanwhile, when you speak to McNamara, you can hand over the holotapes, which confirms his worst suspicions, that the three teams dispatched to the three locations you explored earlier have been wiped out. Unfortunately, though, you'll need even more evidence to finally convince Hardin that it's time to move against McNamara. You can then tell him that you've found holotapes that prove that the Elder did just that. Talk to him all at once, first about the seemingly-possible work-around that would allow McNamara to be removed from his post as Elder due to giving direct orders to subordinates of subordinates.
If you're following our specific directions, then the first person you're going to want to speak to is Head Paladin Hardin, who can be found deep within the bunker, likely somewhere near McNamara's office. Once back at Hidden Valley, head back into the proper bunker, and seek out your two targets.