The latest "NCIS: Los Angeles" featured the team investigating a diplomat's assassination at a consulate in Los Angeles.

In "Tuhon," Sam (LL Cool J) and Callen (Chris O'Donnell) go to Mexico to revisit the first case they worked on together.

They go south of the border to visit Tuhon (guest star Danny Trejo), a retired assassin from Sam and Callen's first case together. Tuhon is suspected of being involved in the diplomat's murder.

It's revealed that Tuhon was set up, and the man who was thought to be him wasn't—it was a man who put on fake tattoos to resemble Tuhon. Tuhon, surprisingly, turns out to be a likable character who is friends with Hetty (Linda Hunt), as well as Sam and Callen.

While waiting to go to a safe house, Tuhon offers some insight into Sam and Callen's partnership. He says they have learned to trust one another in the seven years they've worked together, and that Hetty (Linda Hunt) has trained them well.

They then arrive at the safe house to find that it isn't safe at all.

Russian mobsters show up at the safe house, revealing that they were the ones involved in the high-profile murder. But, as usual, the members of team are able to successfully defend themselves.

When they leave Tuhon, Callen assures him that the NCIS "tribe" is in good hands, no matter what the future brings.

Meanwhile, in Afghanistan, Kensi (Daniela Ruah) is suspicious of Sabatino, who questions Kensi about who she is working for, leading to a heated argument.

She accuses him of being the White Ghost, but he says he's been hunting the White Ghost for weeks. He tells her not to follow him in his search.

When she goes back to the base, she tells her concerns to Granger (Miguel Ferrer), who thinks her accusation is ridiculous. She tells him that Sabatino isn't the White Ghost, and that her one mission is to take out the White Ghost once they find him or her. 

On the next episode, "Fish Out of Water," "The NCIS team needs to determine if an explosion at a fish market is terrorism or a failed drug smuggling deal. Granger and Kensi continue their search for the notorious white ghost with an investigation into a helicopter crash."

Check out the promo for "Fish Out of Water" below, which airs Tuesday, March 4 at 9 p.m. EST on CBS.