The Office of Special Projects or OSP for short is a secondary branch of the main NCIS building in Washington D.C.
It is located in Los Angeles with the current whereabouts being hidden, presumably due to national security reasons.
Unlike the main NCIS office in Washington D.C. with its agents often going into public to investigate various crimes, The Office of Special Projects Building is a field office specializing in undercover work.
It also has a lot of touch-screen enabled technology which comes in handy whenever the NCIS LA team are working on a case.
OSP is a branch dedicated to covert operations that the rest of NCIS do not handle and the branch itself is so secretive that for national recurity reasons, it doesn't officially exist while those who work there are presumably required to use cover stories to maintain the unit's secrecy.
The Office of Special Projects Team is the main flagship team of the Office of Special Projects and is led by NCIS Special Agent G. Callen with Henrietta Lange as the main Operations Manager for the entire Office of Special Projects division.
At some point in 2006, Leon Vance, Assistant Director or possible Deputy Director founded the Office of Special Projects which served as a West Coast counterpart to the main NCIS building located at the Navy Yard in Washington D.C.
Lara Macy was assigned to head the unit with NCIS Special Agents G. Callen, Sam Hanna, Kensi Blye, Mike Renko, Operational Psychologist Nate Getz and Technical Analyst Eric Beale all eventually joining her as well to form the new main Office of Special Projects team.
The team later chose an abandoned office building in downtown Los Angeles at its main base of operations with many missions presumably being conducted there.
In May 2009, OSP and the NCIS Major Case Response Team in Washington D.C eventually formed a temporary partnership with one another as they investigated a Marine's death in Washington which resulted in Special Agents Leroy Jethro Gibbs and Timothy McGee being sent to L.A to work with Macy's team.
Hours later, after the case was solved, Callen was left gravely injured in a surprise drive-by shooting and was left in critical condition.
As a result of Callen's shooting, Macy was reassigned elsewhere while her replacement Hetty Lange served in the position of Operational Manager with Hetty essentially becoming the new boss of the OSP unit.
Furthermore, the OSP opted to leave its current base of operations, leaving the building abandoned and ultimately set up operations at an old Spanish-styled mission located on the outskirts of LA and which had been left condemned after an earthquake.
During that time, NCIS Probationary Agent Dominic Vail joined the team, bringing the field team up to three. He was also partnered with Kensi Blye.
In September 2009, nearly five months after the attack against him, Callen returned to work a month early and also became the new leader of the Office of Special Projects Team which was now composed of himself, Sam, Kensi and Dom with Eric and Nate providing support.
In January 2010, Dom was kidnapped and ultimately vanished without a trace despite the efforts of his OSP colleagues. As such, Callen put out a bulletin for Dom, classifying Dom's status as missing.
In April 2010, OSP met Marty Deeks, a Detective with the Los Angeles Police Department and who was working undercover at an MMA gym that the OSP team were investigating in connection with the murder of a Marine.
Following the case, Hetty who had received a dressing-down from Vance opted to have Deeks appointed to OSP with Deeks serving as the LAPD liaison to NCIS.
Deeks worked another full case with the team before he left to work on an undercover case for the LAPD that required him to severe all contact with his new NCIS colleagues.
In May 2010, OSP learnt that Dom had in fact been kidnapped and was being held hostage by a militant group who were hoping to get a prisoner exchange.
The OSP team eventually found his location and launched an operation in the hope of saving him from his captors before his execution.
Unfortunately, the operation ended in tragedy when Dom was shot after shielding Sam from incoming fire from a lone terrorist .
Despite efforts to save him which consisted of Sam performing CPR, Dom almost immediately succumbed to his wounds and died, leaving the OSP team grief-stricken and completely devastated.
Two days after Dom was buried, NCIS Director Leon Vance personally arrived in Los Angeles to stop Hetty from resigning from her position as Operations Manager with Hetty eventually relenting thanks to Callen's actions.
In that time, the OSP team learnt that Dom had been kidnapped to exchange for Ala A Din Keshwar, a terrorist. The team were able to recapture Keshwar and shoot Army CID agent Rick Medina dead in self-defense, Medina having revealed to have been on Keshwar's pay roll.
In September 2010, after returning from his undercover mission, Deeks rejoined the NCIS team and became Kensi's new partner.
In October 2010, Tech Analyst Nell Jones permanently joined the OSP team.
In May 2011, with Hetty's resignation from OSP, Lauren Hunt became the new Operations Manager. It was later revealed that Hetty had in fact simply left OSP to deal with the Comescu family, a family from Romania who sought to kill Callen but thanks to Callen, Sam, Kensi and Deeks, the Comescu family's plans were abruptly halted.
In January 2012, NCIS Assistant Director Owen Granger arrived at OSP, Vance having appointed Granger as the new Assistant Director of NCIS.
In February 2012, Granger tasked OSP with finding and capturing psychopathic arms dealer, Marcel Jeanvier AKA "the Chameleon" who was also an old enemy of Callen's.
During the resulting, Callen unknowingly shot Jeaniver in the face, the resulting gunshot causing permanent damage to Jeaniver's face while also prompting Jeaniver to embark on a campaign of revenge with Callen as his main target.
While that went on, the Joint Terrorism Task Force conducted an operation to destroy the network terrorist Tahir Khaled was heading with efforts from Sam and Nate.
Things went quiet for a while until in late April/early May 2012, when after learning of a suspect, Dracul Comescu known to OSP, who was a rival of Callen's and who had also gained access to smallpox, Callen and Sam traveled to Hawaii to aid the Hawaii Five-0 Task Force that Detective Sergeant Danny Williams was temporarily leading to help Five-0.
In the process, Callen found and killed his old rival, Comescu, ending the feud that had raged between the two families for many years.
Unfortunately, the celebrations were short-lived as both the NCIS and the Hawaii Five-0 teams later discovered that the virals that they had recovered did not contain any of the smallpox and were left stunned when they found out that a suspect that they had been searching for had already arrived in Los Angeles with nine virals of smallpox, forcing both Callen and Sam to return to LA with Danny and Detective Lieutenant Chin Ho Kelly (2010) coming along too.
After a lengthy investigation with both NCIS and Hawaii Five-0 Task Force forming a temporary partnership to find and stop the mastermind, both sides were eventually successful in diffusing a potential devastating situation and after the case was closed for good, having been solved, Danny and Chin bid farewell to their new friends and colleagues before returning to Hawaii.
About two weeks later, Callen's old enemy, The Chameleon emerged, killing NCIS Special Agents Mike Renko and former Operations Manager Lauren Hunter while also framing Callen so that the State Department could arrest him, leaving the entire OSP team in disarray as a result and Hetty resigning from OSP for good.
However, it was soon revealed that the Chameleon's death had been staged and after everything was sorted out thanks to a prisoner exchange, both Callen and Hetty returned to the team once again.
In late May 2013, Isaak Sidorov, a notorious Russian arms dealer received information from the Chameleon that Sam was a federal agent which the Chameleon later informed Callen was his own act of revenge against NCIS who had given him to the CIA at the time. Sidorov later responded by capturing Sam and Deeks and tortured the two men for information, even going as far to ram a drill into Deeks's mouth as a helpless Sam looked on.
In September 2013, after fighting against Sidorov's thugs, Kensi and NCIS Assistant Director Owen Granger got the location as to where Sidorov was keeping Deeks and Sam captive. Both NCIS agents arrived but Kensi was forced to tell Deeks that they couldn't release him or Sam just first as they had to make sure that Sidorov was still convinced that Michelle on his side and that Deeks and Sam were the enemy.
Once that was accomplished with Michelle shooting Sam and Deeks albeit making sure that their deaths were faked, the NCIS personnel who had been lying in wait jumped into action and were finally to free Sam and Deeks and ensure that both men got medical treatment.
Sidorov was eventually shot and killed, ending the case.
Meanwhile, Hetty contacted Nate, asking him to return to Los Angeles to help Sam and Deeks, both of whom were still struggling in the aftermath of the torture they had gone through at the hands of Sidorov. While Sam remained willing to talk, Deeks completely shut down altogether.