When they finally entered Interview Room One, Baxter was pacing the room in frustration.

"What took you so damn long?" he asked angrily.

Beckett caught Castle's eye and had to bite her lip to stop herself giving him a mischievous smile.

"Mr Baxter," she said, sitting down. "How do you know Ethan Ware?"

"Am I going to prison?" he asked.

"That's not what I asked you, Mr Baxter."

"Am I going to prison?"

"That really depends on how helpful you are," Castle said, pulling up a chair at the big table in the centre of the room.

Baxter frowned but said nothing else.

"How do you know Ethan Ware?" Beckett asked, a little less patiently.

"He pays me to fix things and deliver them for the Department of Health," he muttered.

"Like what?"

"Like those damn air purifiers," he shouted, standing up and running his hands through what was left of his balding head of hair.

"Mr Baxter, sit down," Beckett commanded. He obviously noticed by her tone that she wasn't someone to mess with and did as he was told.

"I had no idea what he was using them for..." he whispered.

"You had a young intern working for you, didn't you? Greg Lawrence?"

"Yes. Is he going to get arrested too? This is nothing to do with him," Baxter said.

"Mr Baxter, Greg is dead."

"No," he moaned, putting his head in his hands. "Because of the virus?"

"Yes. Where did you get the air purifiers?"

"Ware gave them to me."

"Then why did you tell Greg that you had found them?" Baxter looked uncomfortable.

"Because Ware was paying me really well. I didn't want to tell Greg in case he wanted in on the job and I had to split my paycheck with him."

Beckett just raised her eyebrows.

"But when I got my first paycheck, I realised that it had come straight from Ware, not the Department of Health, and that was when I realised that something didn't feel right."

Neither Beckett nor Castle said anything, waiting for Baxter to continue his story.

"I confronted him about it and he told me that it was nothing to worry about. He told me that the whole operation was above board, he just needed a helping hand to fix and deliver a few bits of machinery.

"He got me to connect a timer system to the purifiers. He said it was so that they would turn on and off automatically, you know, to be eco-friendly. So when I fixed the air purifiers up, he would collect them for a few hours. He told me he was taking them to the Department of Health to give them a safety check but now I see that he was rigging them with a damn virus!

"When he gave me them back, he told me where to deliver them. He gave me Department of Health credentials and coveralls and told me he'd pay me once they were delivered. I got Greg to watch the shop while I was delivering them, and now the poor kid's dead."

"And were you just as willing to kill Lloyd Davidson when Ware asked you to?"

"No! I didn't kill him! Ware did!"

"What makes you so sure?" Beckett asked.

"Because on Tuesday he met me on the way to City Hall, he was all worked up, really angry. There was blood on his shirt and he was yelling at me. He told me that he needed the next purifier delivered here, to the precinct."

The interview continued for another twenty minutes before Castle and Beckett finally left the interview room.

"What do you think?" Castle asked.

"It sounds like he's just trying to weasel his way out of the blame, to me, but some of it sounds true."

"I suppose it's possible that Ware was working with Davidson to spread the virus around, but why?"

Beckett thought for a moment.

"Maybe he wanted the glory?" she suggested, shrugging. "If he did kill Davidson on Tuesday, he would have been furious that he couldn't find the cure. Maybe they only created the virus to that they could cure it? Davidson would get recognition for identifying the virus and Ware would get the credit for distributing the cure, essentially saving the city."

"Then why did Davidson swallow the cure?" Castle asked. "If he was Ware's partner in all of this, why didn't he want Ware to get the cure?"

"Maybe he resented him, or they had had an argument."

"Okay, so why, when he realised he couldn't get the cure, was he so desperate to make sure this precinct was infected?"

"Because you're here," Esposito said, nodding to Castle as he emerged from the second interview room. "If he couldn't be the one to save the city using the cure, he was going to try and make himself the hero of your next book by being the one who bravely took charge of the precinct."

"Ware has Hero Syndrome!" Beckett said suddenly. "He set up this entire situation so that he alone could be the one to resolve it!"

"Oh my God, that makes so much sense!" Castle exclaimed. "Did you hear some of his lame superhero lines? 'I'm going to do everything in my power to get everyone out safely.' He was trying to feed me lines to use in my book."

"Did you get a confession out of him?" Beckett asked Esposito.

"We asked him like one question and he folded. Told us everything."

"Why?" Castle asked, slightly disappointed at how easily Ware had caved.

"Because he's not as brave or charismatic as he was pretending. You saw how he acted with the Captain. He's a straight up coward trying to be a hero," Esposito said with a look of contempt.

"Did he say anything about Baxter?"

"Apparently he never told Baxter about his plans; he wanted all the glory for himself."

"So was Davidson in cahoots with him?" Castle asked.

"Nope, Davidson was being blackmailed in to creating the mutated virus."

"How?"

"Davidson's two sisters own a restaurant in Colorado. Ware said that if he didn't make the virus, he would set up a 'terrible kitchen related accident' to kill both his sisters."

"That would explain why he had been such a recluse for the past six months," Beckett said. "He told everyone he was doing research for a paper, but really he was working tirelessly to make sure no harm came to his sisters."

"So Ware did all this just to get some recognition?" Castle asked, shaking his head. "Honestly, very few things are worth mass murder." Everyone turned to look at him. "I'm just saying, there a few things in my life I would kill for, but not fame," he said, glancing to Kate.

"Oh, I am going to take so much pleasure in handing this case over to the FBI," she said with a grin. "We've practically gift-wrapped it for them."

As if on cue, several men in suits came through the door, wheeling in their big smart boards. Kate strode up to them looking a little smug.

"There will be no need for any of this," she said, waving to the high-tech equipment being dragged in to the bull pen. "The man in room one is innocent, your killer is in room two and the guy who created the virus is in the morgue. It wasn't an act of terrorism, it was Hero Syndrome. Everything you need to know is in here," she said, handing one of the men two thick folders.

"Now," she said, turning to her friends, "I don't know about you, but I could use a drink."