On NCIS: LOS ANGELES' fourth season finale, titled "Descent," an explosion in the desert rekindles the search for stolen nuclear weapons and prompts Hetty to shuffle the NCIS: LA partnerships, sending Callen and Kensi overseas and Sam and Deeks teamed up stateside, on May 14 (9:00-10:00 PM, ET/PT) on CBS. Guest stars include Aunjanue Ellis as Michelle Hanna, Christopher Lambert as Marcel Janvier and Timothy V. Murphy as Isaak Sidorov.
Check out a first look below! Photos by: Richard Cartwright/Sonja Flemming/CBS

Kym Jackson, Aunjanue Ellis, Natasha Alam

Aunjanue Ellis, Timothy V. Murphy

Aunjanue Ellis, Timothy V. Murphy

Eric Christian Olsen, Daniela Ruah

Eric Christian Olsen, Daniela Ruah

Massi Furlan, LL Cool J, Timothy V. Murphy, Pasha Lychnikoff

Natasha Alam, Timothy V. Murphy, Aunjanue Ellis

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