This week on "NCIS: Los Angeles," Callen (Chris O'Donnell) learned that he has more blood relatives other than his father, Garrison (Daniel J. Travanti), while Kensi (Daniela Ruah) appeared to be making some progress, which made Deeks (Eric Christian Olsen) hopeful for their future.

A woman got poisoned after smoking a cigarette that had been tampered with, and upon investigation, it appeared as though Callen's father seemed to be connected to the woman, who goes by the name Mary but whose real name is Katerina Polunin (Joan Severance). Katerina has a daughter named Alex (India de Beaufort), and it looked like whoever was after Katerina had begun targeting Alex as his next victim.

When Alex got kidnapped, Callen interrogated his father, and Garrison filled him in on the case. Later, after they found Alex, Callen learned that Katerina was Garrison's daughter and that she was his half-sister. The man poisoned Katerina to lure Garrison out, and when that failed, the assassin started to go after Garrison's family. Callen said that they should tell Alex who they are and how they are related, and Garrison agreed to do so.

Meanwhile, Kensi and Deeks had a lot to celebrate as she started walking again. Though her left hand still needed a lot more work, her friend, Sullivan (Kurt Yaeger) helped her practice daily activities until she was a bit better. Later, Deeks held up his hand, and slowly, Kensi managed to raise her own hand to hold onto him.

Next week, in the episode titled "Sirens," the NCIS team gets a new lead in the ongoing mole investigation after an unknown female assailant kills two men disguised as Sheriff's deputies in front of Callen's home. Elsewhere in the episode, Nell (Renée Felice Smith) visits a prison to interview an inmate withholding information on the department's leak.

In the promo for the episode, Sam (LL Cool J) tells Callen to stay close, and as a threat returns, Hetty (Linda Hunt) says that the wolves are at the door. A woman is seen running towards Hetty before getting intercepted by someone.

It appears that no one is safe as Kensi is seen looking furtively out the window, and later, Sam tells Callen that he's going to find whoever it is that has been going after the team.

"I'm gonna find the head of the snake — and I'm gonna chop it off," Sam vows.

"NCIS: Los Angeles" airs Sundays at 8 p.m. ET on CBS.