Callen returns to the Office of Special Projects team. The actions of a kidnapped navy commander may have jeopardised a military operation aimed at neutralising the threats posed by Mexican drug cartels.

A group of former Navy SEALs, trained by Sam, carry out a hit on a drug dealer. The OSP team investigate the double-crossing and find out that it might run much deeper than they first thought.

A remotely piloted aircraft and a Hellfire missile go missing during a military training exercise. The OSP team enter the shady hacker world in order to attempt to retrieve the equipment before the enemy does.

Walton Flynn, an Iraq war veteran, is tasked with the protection of a visiting Iraqi businessman. When the businessman is found dead, Callen and his team are assigned to find Flynn.

After the murder of a defence contractor in possession of classified information, the OPS team fear the irrecoverable loss of his secrets until they discover a North Korean assassin with connections to Director Vance.

A wealthy bachelor and ex-Marine, killed by a fall from a rooftop, turns out to have been living a double life. The OPS team search for a motive when it is discovered that he was murdered.