Hidoko hasn't checked in, and her phone or tracker don't respond. Sam and Callen go to look for her where she was last reported, with Kensi and Deeks check out her room. Sam and Callen find bone fragments where she was last reported. Hetty gives Kensi the name Arlo Turk. Hetty tells Mosley that Nell is waiting for her in the armory. Turk rents them ATVs but offers little other help. Nell wants Mosley to make a video for her son Derrick, so he will know it's OK to go with the team. The squad gets spotted doing surveillance. Callen's ATV won't start, so they split up. Kensi and Deeks get clear, but Callen and Sam get stopped. Turk drives in and rescues them. Deeks suggests bringing in horses for a riding lesson as a gift for Derrick, to get him to take a ride outside the compound. He wants to do that, but Callen insists Kensi should do it. Turk won't get horses and a trailer for Callen. Turk finds a tracker on his truck, and punches Callen. Turk gets them what they needed, plus weapons. Mosley is missing, and was last tracked near an airport. Kensi talks her way past the gate. Mosley flew to Mazatlan. Wililams is at the compound, and Kensi gets caught. Callen fakes being injured to draw out two guards. Callen takes their pickup and drives in, while Kensi strangles WIlliams and escapes, going to rescue Derrick. Callen and Sam lob gas canisters into the compound. Kensi plays the video for Derrick. Kensi and Derrick go over the wall, and Deeks picks them up. Callen and Sam ride the horses to escape. Mosley is in the chopper and leaves with Derrick. Kensi and Deeks go back for Sam and Callen. A rocket hits their SUV.