Mission Deployment has sent the emergency reconnaissance ship known as the Skylark to pick up the injured Rooks in Deadrock Canyon. When the Skylark team landed, only one injured Rook was found at the crash site, with a horrific tale of what happened to the rest of the group.
Apparently, soon after you left, large Mimics called Black Recluses emerged from the webbed passageways and swarmed the Rooks at the crash site. 10 Black Recluses are scattered across Deadrock Canyon, each with an injured Rook in its claws. Hunt down these Mimics and rescue the trapped Rooks before it's too late.