After leaving Hetty, Callen had gone to debrief Granger following the team debrief, but he couldn't find him and no-one had seen him either. Confused, Callen went back to Hetty but she was missing as well.

Callen was concerned. For all that Hetty p**ssed him off with her recent actions, he still cared very much for her. He respected her as an agent and manager but thought of her as a mother. Until recently, they had enjoyed a family life that no-one within the team knew about, well Director Vance must know, he mused. He missed the times they spent together having a family meal after which she'd read to him in Russian whilst he lay on the couch and relaxed. He hoped that they could find their way back to each other but every time one of them had tried, the other seemed to do or say something and the process had faltered.

He went to find the only person he knew who could help – Nell. Nell, whilst being the newest member of the team, was very much a trusted colleague and pivotal to all that happened. Callen suspected that Hetty was grooming Nell to be her replacement as Ops Manager after she retired. Finding her in the armoury, Callen said "Nell, do you know where Hetty is?"

"No, I don't." Seeing the look on his face she continued "Callen, I promise I'd tell you if I did. I haven't seen her since she stormed out of Ops earlier," careful not to dwell on the earlier incident that had shaken the team.

Callen eyed her quizzically but satisfied she was telling the truth he said. "What about Granger?" When Nell shook her head Callen continued "When I saw her last, Hetty was looking at something she locked away in a box in there" pointing to a drawer in the armoury. "I think their disappearance has something to do with what's in it. I know you have the code – I need you to open it, Nell."

"I can't. Hetty trusts me with certain information; it would be betraying that trust. And I could end up sacked. Or worse" she added for good measure.

"I understand. But Hetty could be in danger and whatever she was looking at might be the key."

By this time Sam and Kensi had joined them. Looking at their expectant faces, Nell caved and opened the locked drawer. "You'd better have my back if Hetty finds out!" she said.

A chorus of 'Of course', 'sure thing', 'y'know I will' greeted her as she handed Callen the box. He opened it & took out the photo. "That's Hetty & Granger with Potter. Taken a while ago looking at how young they are. I wonder where it is and who's the other man" said Callen.

"Looks like Afghanistan or Iran - somewhere like that" said Sam.

"I'll run facial recognition & see if we can come up with a name" said Nell.

As she turned to go, Callen touched her arm. "Nell, thank you. This means a lot. I will have your back, I promise." She smiled at him and said "I know."

It didn't take long to find out the identity of the fourth man. Facial recognition got a match very quickly as he was a former CIA agent. Nell briefed them on what she & Eric had discovered.

"What are we missing here?" said Sam. "Has it got anything to do with the woman who killed Ruiz earlier?"

"It might be connected" agreed Callen. "We've got nothing else. Eric, do we have an address for Brown? If we can talk to him, we might be able to find out. If he's in danger, then Hetty may be a target as well, which is why she & Granger have disappeared."

"Makes as much sense as anything else we have" concluded Sam.

"Let's roll" said Callen to his team as Eric confirmed that the address was on their phones.

Pulling up outside Brown's residence, the team got out of their cars and, with guns drawn, cautiously approached the front door. Callen motioned for Kensi and Deeks to go round the back. When he got the signal from them through his ear wig that they were in place, the teams entered the property simultaneously. Chaos greeted them. Overturned furniture and broken items were strewn across the floor and bullets embedded in the walls. Through their comms they heard Callen whisper 'We've got blood – be careful; they may still be here".

Choruses of 'Clear' were heard as each room in turn was searched and pronounced empty. Callen & Sam came across a bloody handprint on a door jam and a smeared blood trail on the floor and following it into the kitchen, they found a body. Sam bent down and felt for a pulse. Shaking his head, he said sadly "It's Brown, he's dead".

Kensi and Deeks had joined them. Callen said to them "The bad guys burst in, fired, Brown got hit and he crawled to the kitchen. Why? It doesn't make sense."

Deeks said "No, it doesn't and just to write 'Nogales' and 'bo' in his own blood with the last of his strength?"

Callen continued "We know Nogales means walnut in Spanish. But bo? What does that mean?"

Sam said, "Hold on, I've got something here" as he lifted Brown's body slightly. "I've got a wire. Don't move." No-one did but Kensi said "Be careful, Sam" as he traced the wire to a drawer and, very carefully, opened it slightly to reveal some explosives attached to the wire. "We've got a bomb" he confirmed.

Through his comms, Callen contacted Eric back at base. "Eric, we've got a body and a bomb. Get the bomb squad and the coroner over to Brown's address asap."

Cutting comms with Eric, Callen said "So the bad guys positioned Brown here & set him up as a booby trap for whoever found him. Except he wasn't dead and he wrote the warning in his own blood. We now know 'bo' meant bomb."

"So it could've been meant for Hetty?" asked Kensi.

Callen nodded. "Let's get back to base and see where we go from here."

Back at base, in the bullpen, they discussed what they knew so far. Callen said, "Granger didn't want us to investigate Ruiz but we did and he was killed by this mystery woman before we could get to him; both Potter and Brown have been murdered and now Hetty and Granger have disappeared. What are we missing? It has to have something to do with what they were doing when that photo was taken, but what? Nell, do we know where and when it was taken?"

"Yes, it was taken in Karachi in 1985. Other than that, there's nothing else."

"Potter and Brown were retired CIA; we know Hetty worked for them so it is safe to assume Granger did as well" said Sam. The others nodded in agreement. "Back in the 80s, the CIA had its fingers in many pies, none of which they'd want made public" he continued.

"Why hasn't Hetty said anything to us?" wondered Callen.

"CIA might want it kept in-house. Doesn't mean Hetty hasn't left us clues. We've just got to back-track to find them" answered Sam.

Callen's face lit up as if in recognition of something he remembered seeing earlier and he went over to Hetty's office. On her desk was a single walnut. He picked it up and tossed it in his hand whilst he was thinking. Returning to the bullpen he said "Nell, remember that fruit basket we sent Hetty when she was convalescing? It had nuts in it."

"Yes, she sent it back because she's allergic to nuts" confirmed Nell.

"Yes, Hetty's allergic to nuts" said Callen "so why does she have a walnut on her desk?" holding it up for all to see.

"It's a clue?" volunteered Deeks.

"I think so" said Callen. "We know walnut is nogales in Spanish. Eric, can you run a search on nogales and see what you come up with?"

"Ahead of you," confirmed Eric. "I've come up with Casa de Nogales" showing them an aerial view of the property. "It was a presidential home but it's now used as a safe house – by NCIS and CIA mainly. Best guess is that's where you'll find them. Address is on your phones."

"Thanks" said Callen as he and the team left.

Arriving at the property, Callen and Sam overpowered the two agents guarding the property outside and walked them in through the front door to the sound of Deeks saying "Really? That's the best the Agency has?"

Walking in with their guns drawn and the two CIA agents as cover, they were greeted by raised guns held by Hetty, Granger, a black man and a couple more agents.

"Callen, what are you doing here?" demanded Granger, lowering his gun and telling the CIA agents to do the same. Before Callen could answer, Granger turned to Hetty "Henrietta, has this something to do with you?"

"I didn't call them, Owen" she answered in all innocence. "Good to see you Mr Callen. And for the record, it was not my idea to come here."

"Dale Farmer?" said Sam going to the black man and giving him a shoulder hug. "G, this is Dale Farmer, my former CO. He taught me all I know" said Sam proudly.

"Sam Hanna! Heard you were doing well in NCIS. Didn't teach you everything; those ribbons I pinned on you were all your own doing" said Farmer.

"Brown's dead. We found him at his place rigged up to a bomb. A booby trap for whoever came looking for him. Would that be you, Hetty? What's going on, Granger?" demanded Callen. "And why were we kept out of the loop?"

Hetty shook her head sadly at the news of the demise of her old friend.

Dale Farmer answered "Hetty and Granger, together with Potter and Brown, were part of a team tasked with finding and eliminating wanted terrorists. In 1985 they were in Karachi investigating a particular terrorist. Such actions have consequences which tend to come back to haunt us years later. Intelligence spotted a threat and although we're not sure of the connection, it was decided to bring the old team here for safe keeping whilst it was being investigated. Unfortunately, whoever they are got to Potter and now Brown before we could pick them up."

Before anyone could say anything, automatic fire shattered the windows and everyone dived for cover.