Hetty makes an unexpected return to the OSP office to her team's delight.

Callen thinks Hetty is keeping secrets on NCIS: Los Angeles. "Subject 17" is the first episode of the show's 13th season.

While Callen suspects Hetty of keeping secrets about his past and Joelle surfaces in her quest to capture Katya, NCIS must track down an informant whose life is in danger. Also, Kensi and Deeks work to expand their family,

Joelle surfaces in her continued quest to capture Katya.

NCIS must track down an informant whose life is in danger.

Admiral Kilbride and NCIS must track down an informant whose life is in danger.

Fatima and NCIS must track down an informant whose life is in danger.

Callen suspects Hetty of keeping secrets about his past.

Callen suspects Hetty of keeping secrets about his past.

Kensi and Deeks continue to work on expandimg their family,

Kensi and Deeks continue to work to expand their family.

Fatima goes undercover at a rehab facility to question an arms dealer's girlfriend on NCIS: Los Angeles. "Indentured" is the third episode of the show's 13th season.