The boathouse crew gets separated when a retired assassin from Hetty's past is suspected in a diplomat's killing in NCIS: Los Angeles season 5 episode 15.

Sam and Callen head to Mexico to find Tuhon, the assassin from their very first case they worked together seven years ago. The partners have grown immensely throughout their time together.

While they are in Mexico, Nate helps Deeks investigate the Consulate murder.

Meanwhile in Afghanistan, Kensi's investigation into Sabatino comes to a head.

Watch "Tuhon" below or other episodes of NCIS: Los Angeles online.