In the locked building not far from Washington DC.

Tony, McGee, Gibbs, Jenny, Ziva and Kate are captured. McGee and Ziva were thrown into the room at the end of hall, next to him are Gibbs and Jenny and in the third room are Tony and Jenny. The doors can be opened from the inside, but there is no clue given of what is the code, and they are running out of time. All they got for a clue is that there is a code, the same for everyone. And despite the fact, that the walls are thin, they can't say a word or something bad happens. The code's clue is that 0 + 1 = 1. They got 2 hours before the building explodes.

Room 1

McGee and Ziva.

Ziva was pacing in the room and McGee was looking at the clues in case his geek brain can find something. He thought about codes he studied in school, but 0 + 1 = 1 is so easy, and makes no sense.

Tic, toc, tic, toc, tic, toc...

He hears his watch ticking, the time... they are running out of time soon.'' Think Timothy, '' he thought. He heard it was way too quiet, so he turned himself around to find Ziva sitting on floor a meter away from him. He turned back to the paper and started thinking.

Room 2.

Gibbs and Jenny. Jenny was holding the paper with the clue in her hand, Gibbs was next to her.

'' We are screwed, '' Jenny wrote on her phone and showed it to Gibbs, who nod. She leaned back a little, so they had a physical contact. Her head on his shoulder. Gibbs took the paper from her and he focused on the words on the paper. He had seen something like this before, but what was the code the last time ?

Jenny walked to the back of the room, there was a crossword, as another clue. Jenny threw it to Gibbs, who of course remembered the crossword. He took out a pen from his pocket and started filling the boxes.

Room 3

Tony and Kate. Tony looked thoughtful as he read the piece of paper. Kate stood a little away from him like afraid of upsetting him even more, after all it was his idea to come to this building or at least she thought so. Tony held his hand up with a paper on his hand. Kate took it. 0 + 1 = 1. It looked so simple, way too simple.

'' I might know the code, '' Kate wrote on her phone.

Tony gave her thumbs up.

1 hour later...

Room 1

McGee was still thinking about the code, Ziva watched over his shoulder. He was dealing with the leads... There is no way that they could get out with this speed. Ziva was also thinking about the way it is all so simple. Almost the easiest thing to know about maths. Way too simple, but where is the code, the trick, the secret. She stood up and started looking for hints of the code, the trick, whatever thing that should get them out of there. Of course there is the fact that they could say no words between each other.

Room 2

Gibbs was looking in the room for clues. He had seen this before, he had done this before, but when and where it was ? And how to get out ? That is the question, beside they are running out of time and really fast. Jenny at the same time was looking in the room, just to find anything. The crossword gave them a word that says nothing - Fibonacci. Maybe it is the name of any agent or case or whatever, but then of course is the fact that they don't know anything for sure.

Room 3

Kate was writing on the paper she found there... She had the list 0 + 1 = 1... 1 + 1 = 2... 1 + 2 = 3... 2 + 3 = 5... 5 + 3 = 8... 8 + 3 = 13. But that gave them actually nothing. It was way too long and they could only write numbers and it was were unlikely that this was the right code. Beside Tony already tried that, that was the wrong one, now they only had 2 chances left on inserting the code.

30 minutes later...

Room 1

Ziva brought there pieces of papers with random numbers on them such as 0 1 1 2 3 5 8 13 21 34 55. McGee put the numbers on order and looked at them, what they had to do with them ? The code only needed 5 numbers. Which ones are the ones and the order of course. Ziva at the same time kept on looking for anything that could help and they were in serious time problem.

Room 2

Gibbs looked at the word Fibonacci and some random numbers Jenny gave to him. And now he knew where he had seen this before, of course. The code is simple, a little mathematics – Fibonacci numbers. He just had to hit the code. He entered the code 0 1 1 2 3. Error ! What was wrong this time ? It was when Jenny found another piece of paper -

'' You are close to the end. I think you already know what is the code. Fibonacci. Simple maths, now geniuses. You can't hit the same code all the time. Your rooms are in order. Each room has to hit the unique code from that list and it has to be in order. You have to tell others of course... Oh, wait a moment, you can't – you are not allowed to talk. Good luck :) . Hahahahaha...'' The paper said. Since there was a big 2 on the room where they were Gibbs hit the code 5 8 13 2 enter. The door opened. They were free, but at the other side of the door was a surprise.

Room 3

As Kate wrote down everything they actually needed to get out Tony tried their luck. He hit 0 1 1 2 3. And the door opened. They walked out and as thank you Kate hugged him tight, since they didn't know if they can talk or not. He hugged her back – they were saved for now. All they had to do was wait for their team mates to also come through the doors. Since Kate was not willing to let him go or neither was he, they hugged for a long time... until Gibbs and Jenny came out of the other door. Gibbs gave them a nod, which Tony gave back. Kate let him go, but remained close, while Jen kissed Gibbs's cheek.

5 minutes before deadline

Room 1

Ziva found the envelope with the same letter inside that Jenny found. McGee acted fast 0 1 1 2 3. Error ! Then he read it once more – they must be in room 3... in that order. 1 34 55. Enter. The door opened. McGee let a sign of relief – they were out. Outside there was a huge surprise when everybody else was there already. Gibbs and Jenny let out a small laugh, while Kate and Tony had troubles standing up, because they were laughing so hard, still not that loudly.

They all looked up on a screen.

'' Well done team, but I waited more from you Timmy. Such a disappointment. Come back home now, I am so overwhelmed by Ducky's stories... And just for you to know, there was no danger there, just a test that I was ordered to do, and not from this agency. Okay, be back, and remind... no talking still, something hinky will happen then. ''

It was the text that appeared on the screen. Abby was the first thing on their minds after they started walking to the entrance. And then Gibbs knew where he had seen it before...

***flashback***

Gibbs wandered to Abby's lab to see what she was up to. There was a paper with the headline ''Fibonacci numbers'' and down was the long list of numbers. Then he looked at the plasma, there were 3 rooms with cameras, freaky. Then there were envelopes and papers with the same numbers on them. Abby walked to her lab when Gibbs was looking at the papers. He was about to ask Abby something, when she put a finger on his mouth, turned him around and pushed him to go away. He never saw any of them again in her lab and they never talked about it.

***flashback***

Gibbs let out a small laugh at this memory.