Mission 124 - Kill Remy Duvall
Well, it sure is nice to drive all the way back to the Hollow just to drive all the way back to Frisco. You might take care of any lingering side missions before heading back up north again.
When you do, you're looking for a so-called deacon to tell you what's what. These deacons will ambush you like Marcano's retaliation gangs- and like the gangs they tend to strike at the worst moment possible. Try to get to some outlying area without witnesses before slaughtering them, because the deacon takes forever to interrogate. If you don't make it, this is a good time to call in a switchboard marker from Burke.
With the deacon's info, head out to Cleavon Duvall National Park to kill Remy. A standard bit of videogame advice- whenever a path branches, and one branch leads to the objective marker, take the other path.
In this case, it will lead you to parking lot, where you can take out two goons, then climb the hill to cover in some ruins. With a silenced weapon, start picking off perimeter security, working from the edge inward. If the crowd breaks, use Intel View to keep an eye on hostiles. Remy won't flee, so you can save him for last.
After the cutscene plays, you'll learn you have to take out Olivia as well before Frisco is yours. Time for another chat with Donovan.