Trust is at a premium on “NCIS: LA” and, unfortunately for Kensi Blye, she might have placed hers in the wrong person. Sullivan (Kurt Yaeger) is back, but there’s more to Kensi’s (Daniela Ruah) rehab pal than meets the eye. As the OSP works Heather/Rae’s CIA connection, the amputee will morph from injured vet into a spook right before your eyes.

Who is Sullivan?

Yaeger will return to “NCIS: LA” as the series hits the midpoint of its three-episode mole climax (“Hot Water,” “Under Siege,” and “Payback”). After the DEA, ATF, and LAPD converged on Sam (LL Cool J), Callen (Chris O’Donnel), and Deeks (Eric Christian Olsen) last week, the CIA will enter the fray Kensi is kidnapped in this Sunday’s episode.

Sullivan will reappear, but, despite what he told Kensi during their mutual rehab sessions, he’s not a soldier. Instead, Sullivan will reveal himself as CIA Officer Ferris in “Under Siege.”

Has Ferris been playing Kensi all along? Was she merely a part of a broader mission? Is that how he so accurately pegged Deeks during “Parallel Resistors”? While we were off worrying about how he could disrupt the Densi dynamic, Yaeger’s character could have been meddling in something far more nefarious.

On the other hand, Ferris will reveal himself just as CIA Officer Sabatino (Erik Palladino) returns to the City of Angels.

“NCIS: LA” has put a lot of time into building a lattice of trust between Sabatino and the OSP. It would be a shame if that connection was to come crumbling down. Perhaps Palladino’s return signals the CIA’s friendly overtures. Or not. Probably not.

What’s next on ‘NCIS: LA’

After a weeklong hiatus, Hetty’s crew will jump back into the fray on Jan.

29. When Hetty goes rogue and leaves the NCIS team in the dark, the mole will kidnap one of her own. Promos put Kensi in the crosshairs, and with the rest of her team behind bars, the newly returned agent will have to put her skills to the test.

Catch “NCIS: LA” Sundays at 8 p.m. ET on CBS. Click the video to see a preview for the series’ next episode.