The agents of NCIS: Los Angeles are no strangers to undercover work, but Sam Hanna will be taking on a particularly tough mission during "Three Hearts."

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A notoriously tricky assignment, undercover work will be what lands one NCIS agent in the Special Ops team's interigation room. As the team looks into the possibly criminal actions of Agent Paul Angelo (Daniel Henney) and the smuggling ring he was infiltrating, Hetty (Linda Hunt) must insert one of her own into the fray.

"4 days till "Three Hearts"! Sam Hanna...adopts the most dangerous undercover persona we've seen from [LL Cool J] yet," teased writer Dave Kalstein on Friday.

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The former Navy SEAL won't be without support, however. As per usual, Callen (Chris O'Donnell) will have his partner's back, and fans can check out photos of the duo here.

While G and Sam (LL Cool J) may have a rock solid partnership, Deeks (Eric Christian Olsen) and Kensi (Daniela Ruah) are still trying to find a balance between a working relationship and a romantic one. Now that Kensi is back in the field, Kalstein promises that there will be some "soul-searching for Densi."

NCIS: LA airs Tuesdays at 9 p.m. ET on CBS. Click the video below to see a preview for "Three Hearts."

Tags: NCIS: LA NCIS: Los Angeles CBS television