Unlock: Complete Mr. Phillips, Use Trevor
This mission is located at the "Davis Quartz" Quarry, situated southeast of Trevor's safehouse, along the highway. The target is at the bottom of the quarry. Drive over there to meet him. Hit his vehicle or blast his tires if you have to. Grab him when he surrenders and exits his vehicle.
The image featured at the top of this post is ©The Legend of Heroes: Trails of Cold Steel III key art.