A/N : This fic follows on from events in Season 3, specifically Episode 3x10 Sweet Sixteen and 3x24 Snow Day. Hopefully those events will be explained sufficiently in Chapter 2 for readers not familiar with them. However, I must warn you that this fic is a little darker than my previous stories. I have given it an M rating to be on the safe side not only for occasional language but also for mature themes touching on violence (specifically torture) and mental illness (PTSD). I have tried to avoid anything too graphic but I feel it only fair to give my readers due warning.

Chapter 1

Jo Danville tapped her pen nervously against the surface of her desk as she tried to study the ballistics report in front of her. As she looked down the corridor she could see Lindsay watching her. Jo glanced at her watch for the fourth time in as many minutes. She returned to the ballistics report but, despite having read the same words over and over, they still didn't seem to make sense. She couldn't concentrate so she closed the file with a sigh and pushed herself away from the desk. Lindsay was still hovering in the corridor and she could see Danny looking at her from one of the lay-out rooms. She grabbed her phone and pressed her speed dial. She knew he wasn't going to answer but she tried anyway. The phone went straight to voice-mail and the slightly sick feeling in her stomach returned as she listened to his voice for the tenth time that day. She pressed the button to end the call and with a determined expression she rose from her chair and headed towards the AV lab.

Jo saw Adam jump as she entered. His face was sombre and his eyes full of worry She looked at him and then at Danny and Lindsay who had silently followed her. "All right Adam. Do it." Jo watched as Adam turned back to keyboard and hit the enter key. A pop-up box appeared. 'Enter number to be traced.' Adam typed in the number from memory. Jo realized that he had already set it up and was just waiting for her go-ahead. They all waited.

Jo's phone rang taking her by surprise. She glanced hopefully at the caller ID and lifted the phone to her ear. "Yes Don? … No, still no news. Adam's tracing his cell now ... Okay go ahead. Sheldon should be there shortly just in case... " She hung up just as the computer beeped. She peered over Adam's shoulder.

"No signal." huffed Adam. "I'm going to try to switch it on remotely." He tapped away at the keyboard as Jo turned to Danny and Lindsay, her face betraying a little of the nervousness she was now beginning to feel. She looked at her watch again.

"When was the last time you heard from him?" asked Lindsay.

Jo sighed. For some reason she felt guilty. "Friday night. I was in a hurry. I'd promised Ellie that we'd take in that new movie. I guess it was about six-thirty." Jo remembered that she had merely waved at him through the glass. She hadn't taken the time to go in and speak to him. Now she desperately wished she had.

"He was still here at ten." Jo looked at Adam questioningly. "I'd … er … forgotten my keys so I had to come back. He was still in his office but he looked like he was getting ready to leave." Jo tipped her head to one side and was about to ask something else when her attention was drawn back to the computer which bleeped again. Adam turned back to look at the screen. "Nothing. His phone is either out of battery or ..." Adam didn't finish his sentence as he swung back to face the others. He looked even more worried. "Look there's probably a rational explanation. Maybe he went away for the weekend and you know forgot to charge his phone. Maybe he's stuck in traffic." Adam tried to look hopeful but his voice gave him away. "I mean it's only been just over two hours."

"Yeah! But when was the last time Mac was this late for a Monday morning team meeting? He always calls or texts if he's been delayed." Danny looked unhappy. Jo could tell that he thought that something was wrong. "Adam can you check Mac's phone log? Maybe he got a call out?" Adam nodded and turned back to the keyboard. Jo didn't believe that for a minute because she would have heard something about it but she let Adam check anyway.

"Jo do you think we should check ..." Lindsay hesitated not wanting to say it. " … hospitals? You know … just in case?" Jo's lips tightened as she considered Lindsay's suggestion. She didn't want to say yes as she didn't want to think about it. It seemed premature but she nodded reluctantly. Lindsay whirled around glad to have something practical to do. Danny hurried after her and Jo hovered behind Adam as he checked the NYPD switchboard.

"There were no calls from the switchboard. Looks like it's been a quiet weekend. Let me check other calls to Mac's cell. It might take a while."

"Okay Adam thanks." Jo ran her hand through her hair in frustration. "Dammit. Mac, where are you?"

.

'CSI:NY – CSI:NY – CSI:NY – CSI:NY – CSI:NY'

.

Don Flack thanked the building supervisor who handed him a set of keys. "Can you drop them back in my office? Mr Taylor likes me to keep a set for deliveries and you know … just in case." The little man smiled and rubbed his nose on his sleeve. He looked nervously at Mac's door. "Will you be needing me? I've got to keep an eye on the electricians on the second floor." Don indicated that he could go and that he'd drop the keys back as soon as he was done. As the supervisor left, the elevator sounded and Sheldon Hawkes stepped out into the hallway.

"Hey Don. Jo sent me over … just in case ..." Sheldon didn't continue his sentence. Don merely nodded; he didn't want to think about 'just in case' scenarios. He glanced at the four keys on the ring. He selected the key that the super had said opened Mac's door. He opened it up and glanced at Sheldon before stepping in.

"Mac?" Don's voice echoed around the apartment. It was eerily quiet. Both men walked in and looked around. Everything was tidy and clean. The curtains were open and sunlight streamed in through the balcony windows. Nothing seemed out of place.

"Has the super seen him?"asked Sheldon as he followed Don to the right and into the kitchen. Again there nothing out of the ordinary. The kitchen was immaculate; there were no dishes in the sink and the sink was dry.

"No, not since Friday morning when Mac left for work." Don rubbed his hand over the hotplates. Cold. He then checked the refrigerator. Nothing unusual. In fact not a lot of anything. The fridge was almost empty other than some bottled drinks and milk. Don opened the milk and sniffed. A faintly sour smell came back at him. The milk was slightly off. He replaced the bottle and checked the trash. Nothing. They moved down the corridor. Sheldon opened the door to the bathroom and looked around.

"The basin and shower are both dry. So's his toothbrush. Doesn't look he used the bathroom this morning." Sheldon frowned as he looked at Don who had moved across the corridor to the bedroom. He checked the laundry basket. There was little in there other than underwear and a couple of shirts. Sheldon looked at the topmost item and tried to remember whether Mac had been wearing the grey shirt on Friday.

"Bed's made." Don shouted as he moved to Mac's cupboard and slid open the teak-wood doors. Inside Mac's suits were hung neatly in a row, as were his shirts. Shoes were placed on a rack at the bottom and casual clothes were piled neatly on the shelves though one shelf was empty and there was a space on the shoe rack. Don closed the cupboard with a sigh; there was nothing out of place. He wished he kept his place this tidy. He stepped back into the corridor as Sheldon appeared having just checked the spare room. "Nothing."

"Nor here. Where do you suppose he is?" Sheldon's voice was perfectly calm but the look on his face told another story.

"I've no idea. What's in there?" Don indicated a fourth door at the end of the corridor.

Sheldon turned round as though seeing the door for the first time and shrugged. "Closet?"

"That opens inward?"

Sheldon considered it for a moment then reached out and tried the handle. It was locked. Sheldon turned to look at Don who looked at the keys in his hand. Don glanced back at the door. He selected the largest of the four keys and passed them to Sheldon holding the key by his fingertips. Sheldon slid the key into the lock. He seemed surprised when it turned with ease. He pushed the door open and froze. "I'll be damned. I stayed with Mac for almost six weeks. I never knew this was here." Sheldon put his head round the door and spied a light-switch. He flipped it on as Don came up behind him. They both looked at one another and then at the dimly-lit, narrow flight of steps. Above them neon lights flickered to life. Curious they went up the stairs. As they turned a corner, the steps emerged at the far end of a room that stretched almost the whole length and breadth of Mac's apartment downstairs. Don came to a halt next to Sheldon as they both stared around the room in disbelief.

"Oh my God Mac! What the hell have you been doing?" whispered Don to himself.