The investigation of a drive-by shooting has the NCIS team searching Los Angeles for the dead marine's younger brother who may be the next target and the one with the answers.

The NCIS team uncovers an experimental Navy tracking system when a body containing a top-secret residue is stolen from an autopsy room. Meanwhile, Callen challenges Hetty on the rock wall.

After Sam’s undercover mission in Sudan turns deadly, Callen and the NCIS team must track down their missing agent before it is too late.