NCIS: Los Angeles is ready to take on its 150th episode, but all Sam and Callen really want is a day off. Unfortunately for Hetty's agents, no day is complete without a little gunfire.

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Sam (LL Cool J) and Callen's (Chris O'Donnell) mini vacation will take an unexpected turn when the partners receive a mysterious cell phone in "Command and Control." Set to air as season 6's fourth episode, the milestone installment will have the OSP team catering to a stranger's whims in order to keep blithely ignorant civilians out of harm's way.

"Callen and Sam are forced to work on their day off when they mysteriously receive a cell phone and the caller threatens the lives of innocent people if they don't do exactly what he says," CBS teased.

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New promo photos indicate that the disembodied terrorist will attempt to rain terror on a local playground. After all, there's no one more innocent than a child (one of whom will be played by O'Donnell's own daughter). Unfortunately for Deeks (Eric Christian Olsen), Kensi (Daniela Ruah), Sam, and Callen, they will fail at least once before the episode ends.

"Command & Control" will air on Oct. 12. Catch NCIS: LA Mondays at 10 p.m. ET on CBS.

Tags: NCIS: LA NCIS: Los Angeles television CBS