As Gibbs hung up the phone after talking to Ducky, he froze for a moment and wondered how his whole team seemed to change so much and so fast. Since his return from Mexico, Ducky seemed to be furious with him. And, that issue was finally put to rest for good just a few weeks ago.

Timothy McGee, our Probie, wrote a best-selling novel, which really is realistic fiction based upon his teammates' personal lives. If that wasn't confusing or fascinating enough, the fact that our computer genius has such an artistic and imaginative side as well as the already well established mathematical skill and logical sense, definitely is.

Gibbs shook his head, joking to himself at first, then becoming increasingly overwhelmed with frustration. He just didn't understand how all this happened in just the four months he was away. The part that concerned Gibbs was that many of these changes were taking place right in front of him, with people he knew well for a while, and he hadn't noticed the changes until now.

What could be going on with Tony? He wondered. This doesn't make sense. Is it possible that Ducky just missed something during the exam? And, another question is -- what is Tony investigating for the Director? Gibbs squinted and shook his headed in frustration, wondering if there could possibly be a link. What is going on with my team? Gibbs continued to shake his head in confusion.

The next morning, as Gibbs and Ziva met at the car in the parking lot of a Edenvale motel, they got into a very detailed discussion about coffee. When getting into the car, Gibbs was surprised by Ziva's questions to him about Tony. She was very concerned that he was unreachable by phone.

"Look, Tony's been very secretive lately, and for a man who can't keep what he had for breakfast a secret, I think it's scary." Ziva tried to support her argument and push for Gibbs to be concerned as well. "What's scary is your persistence." Gibbs retorted. Gibbs was overwhelmed with frustration that his job required him to be focused on a case, while he personally needed to be focused on the concerns that he had over his team. The growing concerns about his team were becoming overwhelming. Once he was back on the highway, Gibbs hit the steering wheel in frustration, which caught Ziva's attention, who had just been staring out her side window.

"Gibbs?" Ziva asked in concern.

"I know." Gibbs said back to her, with no explanation. Although she never made eye contact, Ziva nodded in understanding that Gibbs was just as concerned as she was. They drove to the rest of the way in silence, and Ziva had spoke very little to Gibbs the rest of the morning.

After meeting up with McGee, who had spent most of the morning with Edenvale's forensic expert, Ruby, the team drove back to Washington D.C., after collecting the evidence.

Back at NCIS headquarters.

McGee and Gibbs had just arrived and were now riding in the elevator. Gibbs was looking over a file, but then closed it up momentarily.

"McGee?" Gibbs gave him a confused look. Gibbs knew that this was the wrong time to do this and that there was a case for them to be investigating right now. However, since they were back at headquarters, he felt an investigation into his team members was more of an immediate priority.

"Have you noticed any "out of character" behavior from DiNo. . .any of your team members?" Gibbs asked.

"Well." McGee tilted his head to the side and gave a gigantic smile. "I did notice that you have been . ." McGee started but stopped when he saw the "not me" in Gibb's all- serious stare.

"Ah, Ziva and Tony did try to kill me last week, when we were driving the truck to the crime scene high school in Quantico." McGee suggested trying to lighten the moment and not sure of what Gibbs was looking for. "They hate me right now." Gibbs stopped and tried to read him for a moment.

"Tell me something I don't know. You wrote a fictional book about their personal lives together, McGee." Gibbs added with a slightly lighter expression.

McGee then shook his head back and forth, trying to think of anything out of the ordinary that Gibbs might be looking for.

"Something unusual, something unusual." McGee said aloud as he processed what Gibbs was asking him. "Oh, I did see. . ." McGee started, but then stopped when he remembered who he was talking to. "uh never mind." He shook his head and then looked to the wall of the elevator.

"Spit it out, McGee." Gibbs ordered, giving him an angry look.

"Well, several times now I have actually seen Tony, at least appear like he was sleeping at his desk, during the day, which is really odd for someone who normally has almost too much energy." McGee was at a loss for words trying to explain Tony's endless amounts of energy and his normal child-like behavior. "I am sure he wasn't though, Boss." McGee winced at what he had just done and tried to consider what Tony would do to him, if he found out.

"No, he probably was." Gibbs said quickly, nodding in agreement with McGee's statement very calmly, which amazed McGee. "Anything else?"

"Ziva and Tony seem to be acting like an old, married couple lately." McGee shook his head as he made that comment. This earned a smile and nod from Gibbs.

"I have noticed that, too." Gibbs finally responded with a grin, as he reopened the file.

The elevator door dings.

McGee and Gibbs exit the lift and head toward their desks. Tony is finishing up his cell phone call, as they approach him.

"Hey. You taking calls again?" Gibbs asks Tony as he passes him."I never stopped, Boss. Why? Did I miss your call?" Tony asked, slightly worried."No, not mine. What'd you find out about Masoud?"

The team began focusing on their case again, as Ziva approached and announced that Masoud was in the interrogation room. She angrily approached Tony, who tried to play innocent.

"Why didn't you answer my calls?" Ziva asked getting right into Tony's face." Gibbs just asked me that. I think I had it on silent." Tony answered in a casual tone, but then swallowed hard, when he remembered what Ducky had said Ziva was doing the night before. "Your other phone is never on silent. Hmm." Ziva retorted and walked away.

Tony sighed, knowing that he needed to apologize to her and that avoiding her was not going to fix anything. He listened as McGee was phoning Ruby, telling her to come to NCIS headquarters. He stared at him a moment, and then took off after Ziva before she reached the interrogation room.

"Ziva!" Tony yelled to her as he saw her exiting the interrogation room.

"Tony." Ziva said, indicating that she was now annoyed with him as well as angry.

"Listen, Ziva, I am . . ." Tony started to deliver his apology.

"Yeeees, Tony?" Ziva did not understand why it was taking so long for Tony to apologize for ignoring her phone calls.

Tony decided to start his apology from a different angle.

"I had a talk with Ducky yesterday." Tony started, but then got straight to the point. "Why do you think I was re-infected with the pneumonic plague, Ziva?"

Ziva was surprised by his question and wondered how he found out about that, since Gibbs did not seem interested in her concerns. She squinted her eyes at him, waiting for him to continue.

"Ziva, if I ever got re-infected with pneumonic plague, I would probably d. . . I wouldn't be at work, anyway. That little paper bag didn't have a stool sample inside, Ziva. It was a jelly doughnut." Tony looked up and away from her, as he confessed. The guilt continued to consume him. He then sucked in a deep breath and looked directly at her, knowing that he needed to do this.

"Ziva, it was very wrong of me to lead you to believe that I was having medical tests done. The whole thing was a tasteless joke, and I shouldn't have allowed it to continue. I am sorry." Tony said slowly and sincerely and in a manner that seemed to be truly difficult. He also continued to appear overwhelmed with guilt.

"Tony!" Ziva facial expression indicated that she accepted the apology, but it did not put her worries to rest. "What type of illness do you have, then? Why are you always getting phone calls from a hospital? And, I know you really did go to the hospital that day because I followed you, Tony!"

Just then, the door to the interrogation room opened and Gibbs stepped right between them. Gibbs gave both of them a hard stare but seemed to direct it more at Tony, which indicated to Ziva that she should leave. Since Ziva now knew that Gibbs was just as concerned as she was, decided to leave Tony with Gibbs. The stare that Gibbs was giving Tony seemed to be preventing him from moving, as well as breaking eye contact. Gibbs continued to stare at him until Ziva was out of sight.

Gibbs' stare softened and he arched his eyebrows, as he asked, "Why don't you tell me the answer to Ziva's questions, Tony?"

"I uh. . .I was, uh, just messing with Ziva, Boss." Tony winced and looked down as he said this, hoping that Gibbs wouldn't notice that he was hiding something from him.

"Did you get enough sleep last night?" Gibbs redirected his questions.

"Yeah." Tony then looked back up at him and laughed lightly at the completely unexpected question.

"Did you take any of the sleeping pills that Ducky gave you?" Gibbs asked, as he gave him a concerned look.

"Uh, no, Boss, I didn't need them." Tony answered very confused. He started looking down and to the side, trying to figure out why Gibbs was asking him this. Gibbs seemed to notice his confusion.

"What is going on with you, Tony? Why are you always getting calls from a hospital or going see a doctor?" Gibbs asked softly looking at him with an extremely concerned look and trying to establish eye contact. Tony bit down on his lip instead of answering.

"I asked Ducky to examine you." Gibbs finally answered for him. Tony's eyes narrowed slightly and his jaw dropped from his confusion. Tony then looked straight down.

"Uh, why did you think that was necessary, Boss?" Tony asked and he straightened, his expression showing some embarrassment and guilt.

"I never thought you were having a relapse with y-pestis." Gibbs threw the question back at him. "But, are you sick?"

Tony simply looked at him with wide eyes and shook his head answering no. He then looked back down to avoid Gibbs' stare.

"Talk to me. . ." Gibbs pushed. "DiNozzo."

"I am not sick, Boss." Tony said looking back up at Gibbs, hoping Gibbs would leave it at that. Gibbs once again tried to keep eye contact. As Tony said this, Gibbs gave him a hard stare again, letting him know he wasn't off the hook.

"Are you catching up on sleep at work because the director has you running too many of her errands?" Gibbs asked sarcastically, as his tone got angrier. "Or, is there really some type of health concern, Tony? Gibbs asked much softer.

Gibbs' stare continued to eat away at Tony, as he expected an answer. Tony swallowed hard and finally looked at Gibbs.

"Uh, . . .I don't. . .I don't have any health issues, Boss, really." Tony answered then quickly winced and looked at the ground. Tony knew that Gibbs planned to go to the director then to end the undercover assignments.

"Tony." Gibbs repeated. "Tell me what the answers are to the questions Ziva was asking you." Tony looked at him apologetically, then he titled his head back down. Tony could sense Gibbs moving even closer to him. Gibbs continued to stare at him, as Tony was being unsuccessful in avoiding eye contact.

"I am watching you, Tony." Gibbs finally said to break the uncomfortable silence. This discussion wasn't going anywhere. Do I even know Tony anymore? I just ordered him several times to tell me, and he didn't follow that order. He used to be so much easier to read. Gibbs finally ended the hard stare he was giving Tony.

Knowing that Masoud was still in the interrogation room, he refocused on the investigation, opening the door to the interrogation room, again.

"DiNozzo, go put our suspects up on the plasma. I'll be up there in just a minute." Gibbs slightly grinned at how quickly Tony responded to that particular order. As Tony was ready to take off at full speed, Gibbs grabbed his arm, so Tony turned to look at him.

"Tony." Gibbs said and gave Tony such a concerned look.

"I really am fine, Boss. Thanks for . . ." Tony said in a manner that wasn't overly convincing to Gibbs. Tony trailed off, as he could see that Gibbs was becoming irritated now with what he was and was not saying.

Tony entered the bullpen. Still feeling guilty and now embarrassed, he tried very hard not to establish eye contact with Ziva, who he could tell was watching him closely. As Tony approached the plasma, Gibbs walked in and stood beside him. Ziva sat at her desk trying to read the two men, but they were both so focused once again on the case that she refocused as well. After Gibbs, Tony, Ziva, and McGee questioned Raines in the conference room, Ziva and Gibbs went to pick up the two other suspects.

In the car, right outside the suspects' home."Uh, Gibbs, about this morning." Ziva tried to explain why she was so concerned about Tony at the moment. "I thought you sent Tony back because of his um… illness."

"His illness?" Gibbs asked, slight irritated that she was still pursuing this. He was irritated because he still had no explanation to put her concerns to rest, either.

"He has two cell phones. Makes furtive calls to hospital. Goes missing for hours. Always lies about where he's been. I mean, he doesn't even talk about women anymore. The only logical explanation is that he's receiving outpatient treatment for a serious medical problem." Ziva explained. Gibbs processed and was agreeing with what she had said. Tony did get through to her that it couldn't be "y-pestis", but she was still convinced that he had some type of health concern that he was keeping a secret.

"That's not the only explanation." Gibbs said, but unconvincingly, since he didn't know the real reason. After making that last statement, Gibbs hoped that Ziva would stop worrying, but at the same time, he hoped it was true. He then redirected Ziva toward arresting their suspects. After completing their task and returning to NCIS, they exited the elevator to see that McGee was leaving with Ruby. As they had a polite exchange, Ziva asked McGee if he knew where Tony was.

"Tony left shortly after you did. I haven't seen him since." McGee answered as he and Ruby got into the elevator together. Ziva turned to look at Gibbs, who had a distant look on his face. He sighed and quickly arched his eyebrow at Ziva heading for his desk, as Ziva watched him.

The End of Tony's Evolution, Part I

Part II will focus on later episodes in season 4