Mike's thirst was raging; it was what compelled him to force sluggish limbs to cooperate, pushing himself out of bed. He'd been trying to sleep for about three hours, only catching a few minutes rest in between tossing and turning.

Michelangelo staggered across the bedroom he normally shared with Donatello, and out into the hall. When he glanced down over the railing into the living area, he saw brighter lights coming from the Lab than usual. Something must be up. Shouldn't be running that many lights in the middle of the night.

Mike looked at the stairs dauntingly, and sighed. He wasn't going to be able to ignore these symptoms anymore. His head was pounding - it had been for several hours. He'd thought he could sleep it off, but the throbbing only increased in that time.

Slowly he eased down the steps, leaning heavily on the railing. Breathing in and out softly, he padded across the room, heading for the kitchen. Splinter looked through the window of the lab, seemingly attracted by his movement. Mike waved to him innocently and kept going.

He flipped on the kitchen light, and the focused brightness dazzled weary eyes. Taking four more steps, his knees suddenly buckled. He stopped with a jerk and shuddered. "Aw, shell."

The turtle reached for a chair, since it was the closest object which could support him. He was almost afraid to sit down at this point, because he wasn't sure if he would be able to get back up. As thirsty as Mike was, the couch was calling his name more than a hard kitchen chair.

The orange-masked turtle tried to straighten upright, but closed his eyes when he found that the room was spinning. Gotta sit down, numbskull. No choice.

His head twisted dangerously when he heard the soft squeal of the door. Splinter walking into the room removed any chance of hiding what was going on.

"Michelangelo? What is the matter?"

Trembling uncontrollably, he took a sharp breath. "Room...spinning..." he admitted.

Splinter swiftly grabbed his shoulder, guiding him into the chair he'd been gripping.

Even when Mike surrendered to sit down, he was still shaking. "I can't stop."

His Master pressed a hand to his forehead, and the turtle noticed him wince.

"You are much hotter than you should be. When did this start, Michelangelo?"

"Few hours ago, but it wasn't this bad. Thought I could sleep it off. But I just feel worse now."

Splinter grabbed a bottled water from the fridge. The rat encouraged him to drink what he could, and assured him he would be right back with Luke.

The doctor was scanning something on the computer screen, but was immediately distracted by the way Splinter reentered the room.

He turned on heel to face the rat. "What's wrong?"

"Michelangelo is in the kitchen - he is exhibiting symptoms like Donatello. He could barely stand."

The doctor swore, and then quickly apologized. "Has he been around Leo or Raph very much?"

"I do not think so. He has spent most every waking moment with Jenna and..."

"Donatello," Luke finished. "Oh...boy. We'd better get him in here and compare them side by side. This is probably something contagious."

They hurried back to the kitchen, and found Mike slumped over so far he had nearly fallen out of the chair.

Luke knelt swiftly on the floor beside him, carefully lifting his chin. "Hey, Mikey. How long has this been going on?"

"A few hours...give or take."

"You should have spoken up," Luke said sternly.

"You've been a little busy. I didn't expect it to get this bad. I'm sorry."

Luke wrapped an arm around his shell when the trembling intensified. "Okay, look, Don is sick too. He started spiking a fever about two hours ago, I reckon. I'm guessing this could be contagious, so I'll take you to the Lab, and your brothers will have to be off-limits."

Between Luke and Splinter they half-carried the weakened turtle, taking him to another bed in the Lab. When Luke got a temperature reading, he physically turned away to hide his face.

Splinter was applying a cold compress to Mike, but silently joined the man when he sensed how troubled he was.

"What is it?" the rat whispered.

"He's got a higher fever than Don," Luke told him quietly. "We have to act fast. It's at a dangerous level."

"Do we need Donatello's help?"

"I hate to bother him, but yes. We should probably at least confer with him about his formula."

"Um...guys?" Mike quavered in a way that was very sad to hear. "I'm feelin' kinda alone over here."

Luke strode to him. "Sorry, Mike. You have a really high fever. I need to get you set up with an IV."

"Don't give me as much as you gave Donnie. I can't...I'm not supposed to."

Splinter came around his other side. "What are you talking about, my son?"

"He's right." Don cleared his throat in what seemed an attempt to gain volume. "Our levels of tolerance are completely different."

With Splinter in place by the younger turtle, Luke went over to Donnie. "I knew you weren't asleep."

"All of us have had hydralin before, except for Mike. I finished the formula out of necessity when Leo and Raph both got sick around the same time. I ended up with it too since it was contagious, but not before I had the drug in place. Mike never got sick. He never had the drug. All three of us have a semblance of tolerance, whereas he has none." The speech appeared to take a lot out of him, and Donnie was forced to lay his head back down.

"Don, his fever is higher than yours. It's not looking very safe," Luke warned him.

The purple-masked turtle closed his eyes for a few seconds and opened them again. "It's risky, but we don't have a choice, do we? Use your best judgement, Doc. You're gonna have to start him on the same thing gradually, because it's going to be a shock regardless. I wish I could help you but...I won't stay awake much longer, no matter how hard I try."

Luke lightly grazed his forehead, sharply drawing away after a second.

"I know it's rising," Donnie acknowledged. "You're going to have to increase my IV too."

"Donatello, say something!"

"Focus on Mike. He needs you guys more right now."

"That doesn't mean you don't matter. I'll increase your levels, and send your Sensei back over."

After making needed adjustments with the machine, the doctor crossed the room to talk to Splinter for a moment. The transformation of the rat's expression was so startling, it stopped Luke in his tracks.

"This is my fault," Splinter explained softly, so only Luke could hear. "Donatello warned me years ago about it, and I would not listen. Michelangelo is at greater risk now, because I would not let him take appropriate action."

After a beat of hesitation the rat shook his head. "Donatello asked if he could use a specialized technique to start building a tolerance in Michelangelo. He had a healthy childhood, certainly the best immune system among them. I would not allow it - I thought it was unnecessary. Thus, he is not prepared to handle the drugs that he needs to receive."

"Master Splinter, it isn't your fault they're sick. Now isn't the time to blame yourself. There is some calculable risk to take with both of them. Donnie is getting sicker too - I just had to increase his levels. We have to attack the fever and hope for the best. Will you keep an eye on Don for me? I need to get to work on Mike now."

They watched the pair very closely for the next couple of hours. Mike fell asleep quickly, but after a while, Luke realized he wasn't responding to any kind of outward stimuli.

Splinter had noticed him hovering with an air of concern. "What is wrong?"

"He's completely out of it. I'm going to hook up some monitoring equipment, to be sure I have a handle on how his organs are functioning."

Meanwhile Don was having reactions of his own, his body seized intermittently by violent convulsions. He was quiet for a few minutes as though sleeping, only to cry out and tremble over things that only he could see.

Splinter remained glued to the purple-masked turtle's side. He glanced up as Luke made his way over a short while later.

"He is hallucinating, Doctor Barrows." Splinter rinsed a rag in the water he'd prepared, applying it to his forehead. "This feels inadequate."

"You're doing the right thing," Luke told him. He was nervous, but tried to keep his demeanor calm. They kept their vigil all night, hoping, praying, and waiting for the fevers to break.

Raph woke with a start around 5:30 AM. He sat up at once, shutting off the vibrating alarm on his cell-phone. He crawled out of bed carefully, trying not to wake up Leo on the top bunk.

The red-masked turtle walked down the hallway stiffly, and peeked into Mike's and Don's room when he noticed the door ajar. One glance confirmed it was empty. He grunted in sheer irritation - Mike had been carrying too much of the load, and he'd promised to follow up with Donnie this morning.

Raphael breezed down the stairs, making a bee-line for the Lab. As soon as he glanced in the window, Splinter rushed to the door.

"Away from here, my son."

"Master, what's going on? I told Mike I was–"

"Go! " he commanded, jerking him closer to the kitchen away from the Lab. "Your brothers are sick, and it is contagious. You and Leonardo cannot go to them."

Don was the first one to stir that morning, but Luke wasn't positive if he was actually waking up. The man rinsed a cloth under cold water in the sink, and sat down beside the turtle. When soft coolness brushed Donatello's head, dark eyes fluttered open.

"Doc." His voice hardly registered. "Is Mike okay?"

"His fever finally broke about an hour ago. Yours went down just after dawn."

"Is he okay?"

"Take it easy, huh? His vitals are stabilizing, but he's still pretty far under."

"I was afraid of that."

"Try not to worry. His body is strong, and there's no reason he won't pull through."

"Thanks, Doc. I'm really sorry I couldn't help."

"You did help, Donnie. You also had a really rough night. You need sleep, so no more talking."

"Okay," he whispered, relaxing as Luke lightly massaged his bad shoulder, easing the building tension. In under five minutes, he was back asleep.

Donatello woke up again in the mid-afternoon. Rising carefully with his good arm, he propped himself up so he could see Splinter sitting over by Mike.

The rat rose at once and hurried to him. "Good afternoon, my son. I have been told you are not allowed to do anything. Lay down. You are weaker than you realize."

"Is Mike still out of it?"

Splinter nodded. "But he is stable. That is the important thing."

Donnie looked at the ceiling briefly, and then back at Splinter. "Are Leo and Raph okay?"

"They have not experienced any symptoms so far."

"That's good. I bet Luke didn't expect to get this kind of workout."

"It is fortunate that he was here, my son. I asked him to get some sleep about five hours ago."

"Yeah...you guys were up all night again. Did you sleep at all yet?"

"After Michelangelo's fever broke, Luke sent me. Now I have relieved him."

"I don't really remember last night, but it feels like I didn't do much sleeping. What happened after he increased the IV?"

Splinter paused as though to consider his words carefully. "You had a negative reaction. You spent most of the night going through a mixture of bad dreams and hallucinations."

"Did Doc take notes?"

"His notations were frequent. It is nice to have you back, Donatello."

"Well, let's just see if I can stay back this time."