"This was definitely the Earth. Or rather, it most definitely was not." – Mostly Harmless, by Douglas Adams

"It's Dick Coonan!" exclaimed Beckett as she and Castle walked away from the OCME. She kept making wide gestures with her hands and was walking very fast. Castle walked a few steps behind her, partly because she was walking faster than him and partly because her wide gestures kept smacking him in the face. She seemed not to notice. "Dick Coonan killed Basher!"

"Right," said Castle, opting to act like he knew what was going on. "Who is he again?"

"Coonan killed my mom," she said. Her eyes darkened like she was sad, but the electricity of realizing that she knew Alan Basher's murderer was pumping her full of an energy that could not be dimmed.

"Your mom is alive," Rick reminded her as they crossed the street. He stuck closer to her on the crosswalk, worried that in her energetic state she would misstep and get struck by a car. As a result, he was still standing close to her when she whipped around on the other side of the road and inadvertently thwacked him with her wildly gesturing hand.

"Yeah, well Esposito still thinks Ike Thornton is dead," she said, not even noticing that she'd hit her partner. "Hell, maybe he is. Montgomery's alive. No reason Coonan shouldn't still be alive."

"I have no idea who you're talking about," he said, rubbing his injured nose.

"In fact," said Beckett, coming to a complete stop in the middle of the sidewalk, "if my mom never died, then I never ran into Coonan, so of course he's still alive." Castle pulled her over to the side of the pavement, against the wall of a bank, to get her out of the way of foot traffic.

"Hey," he said. He put a hand on her shoulder to keep her from going forward. "Kate, can we just… just stop for a sec?"

"Why?" she said, brushing his hand off of her shoulder. "I know who killed Basher, we should be going and arresting him!"

"Okay, first of all, we're not really cops, remember?" said Castle, replacing his restraining hand on her shoulder. "And second, you shouldn't know who killed Basher. Do you get that? It makes no sense. You have no reason to know who Dick Coonan is, far as I can figure."

"But…" She took a deep breath, leaning against the wall behind her. She hadn't exactly considered this before- she'd been so caught up in getting trapped in this topsy-turvy world that she hadn't stopped to realize that she was the odd one. Maybe to her it seemed like she was the only one who was right in a crazy world, but that wasn't how everyone else saw it. It wasn't how Ryan and Esposito saw it. It wasn't how Castle saw it.

"Kate, I'm worried about you." He took a deep breath, like he was preparing to go underwater. "I think it might be best if you went back into rehab."

"No," she said, shaking her head back and forth in quick, repetitive motions. "No, no, I can't go to rehab." Great. Now not only am I losing my partner, but I have "Rehab" stuck in my head. "They'll call me crazy, they'll send me to a mental institution!"

He took her elbows. "Look, I'm sorry, but maybe that would be best."

She shook him off of her for the second time. "You don't get it! Nobody understands what's happening to me!" She sighed and shook her head, forcing unshed tears of frustration back into her head.

"Then… explain it to me," he pleaded. He reminded her of the shipper name he'd made up for Esposito and Lanie, and she almost smiled. It was just more proof that she didn't belong here, in a universe where Esplanie didn't even kind of exist, neither the word nor the couple.

"Okay," she said, running her fingers through her hair as she tried to figure out how she was going to- successfully – explain her situation this time. "You know that movie Back to the Future?"

"Yeah."

"Oh good, that still exists." He nodded along, but he didn't really look sure of where she was going with this. "Well, there's that part where Michael J. Fox goes back to 1985 but everything's messed up, and his dad's dead. Nothing's the way it's supposed to be but he's the only one that knows it." Castle stared at her. "That's how I feel!" said Kate. "Only I have no idea what's going on because I never agreed to this! I didn't climb into any flying DeLorean. I didn't ask for this."

"Sometimes you can ask for something without realizing what you're really asking for." He said it like the line had just popped into his head, like it was a piece of advice he'd heard repeated so many times to him that it had lost all meaning.

But it meant something to her. How many times had she missed her mother? How many times had she struggled to fall asleep against the tears, wishing that her mom had never been killed?

It all fit together- if her mom had never been killed, then she never would have killed Dick Coonan. And if her mother had never been killed, then it made sense to believe that Bob Armand had never been killed either, which was why Montgomery was still alive but in a lower position. If her mother had never been murdered, then she never would have become a cop, never would have met Ryan and Esposito and Lanie. She never would have been partnered up with Castle.

"Damn ripple effect." Castle patted her on the shoulder like he was bringing her back into this strange reality.

"You want to head back to my apartment and… and watch Back to the Future?" he suggested. She laughed.

"Yes and no," she said. "Let's go back to your place and reassess the case, but I think I'd rather focus on my own paradoxes for now instead of dealing with Doc and Marty's." He nodded and the two of them headed down the street towards Castle's loft.