"Time Will Tell" continued one of Castle's best season to date. It was classic Castle with a sci-fi twist, some Casketty future goodness and a father/daughter moment that broke my heart.

Let's start with the sci-fi…

Castle finally got his time traveling killer. Simon Doyle was exuberant and determined enough to sell his story, yet crazy enough to make me question it too.

The thought of future Energy Wars was just believable enough to be scary and I appreciated Castle asking the questions about the butterfly effects of changing the time stream and Doyle's explanation that while some minor changes were self-correcting, others could undeniably change the future.

As usual, Beckett was the skeptic but I liked that. Someone has to look at the evidence logically and not get swept up in the fanciful theories. As a cop, that's her job. I was relieved when Beckett pointed out that the way Simon knew the numbers 1258 were because he'd been to the crime scene and seen the victim's watch stopped at 12:58 a.m. 

For every crazy sci-fi theory, there was also a logical explanation, if you were willing to look. 

The story also explored the ripple effect of not only time but people, as Dr. Wickfield wasn't the person who solved the energy crisis or stopped a supposed future war but his work may have inspired the kid who one day would.  The effect you have on those around you is something you can never predict. 

And for us sci-fi geeks, how cool was it to have Tim Russ who played Lt. Commander Tuvok on Star Trek Voyager as Dr. Malcom Wickfield? (Yes, I really did yell out, Hey it's Tuvok! when I saw him on the screen.)

Also, who would have guessed that Espo was a Dr. Who fan?

On to the Casketty future goodness…

Beckett got tackled by the creepy Garrett Ward and Castle came to her rescue, only to be almost strangled to death but the super soldier from the future. I was hoping for more of a moment where Castle and Beckett made sure the other was OK after the attack but with so much going on it wasn't meant to be. 

Instead, we got something even better.

Simon not only told us that Rick and Kate would indeed get married but that Castle eventually begins writing serious literature (Hey, I like the mystery novels.), she becomes a senator and they have three kids. I found it telling that Castle focused on Beckett becoming a senator while she appeared more shocked by the three little rugrats they'd be having. I would have loved to have seen a more private discussion about that one later.

And yes! I really did want to know the kids names.

However, I did love it when Beckett spilled the coffee on the note and made the connection between her actions and the picture from the future. Even the most logical of us have to believe that there are some things in life we cannot understand.

And I know Castle was still reeling from Simon's apparent disappearance but when your fiancee mentions a plan for a warm, cozy bath I believe the expected response is, Can I join you? Of course poor Castle had other things on his mind.

Like Alexis…and Pi…and the future coming too soon.

Thankfully, this episode answered some questions that have been lingering all season. First, that Alexis is at the loft because the college semester hasn't started yet. That made some sense if you figure at the start of the season Beckett had been in training for two months. That would have started us off somewhere in July in the Castle time line. 

I was also glad to hear that Alexis wasn't expecting Castle to pay for her new place with Pi. That would have been too difficult to wrap my mind around. 

It was good to see that Castle finally hit his limit of having the free loading boyfriend sleep on his sofa. Even the most patient parent has their breaking point but he wasn't exactly thrilled with the resolution as he told his daughter in this Castle quote...

No Alexis, I do trust you I'm just saying deciding to share an apartment with someone you met on a banana plantation a month ago just doesn't strike me as the smartest decision you've ever made. | permalink

I also loved Castle's response to Ryan when he broke the news…

Ryan: And you're letting her?
Castle: Well apparently the only way to stop her is by locking her up but according to Miss By-the-Book here that's unlawful imprisonment. | permalink

The final scene where Castle had to watch Alexis walk out the door was truly heartbreaking. The realization that all those moments between he and his little girl were long over flashed through his eyes and boy did it hurt. Having her go off to college was one thing. Having her move in with a guy clearly had a deeper impact.

For Castle it was far too soon. For Alexis it was time to move out on her own.

The good news for Castle is that Pi doesn't seem truly harmful, just kind of goofy…and a guy. And if it all falls apart, she can always come home.

The good news for fans is that Castle and Beckett should have a lot more privacy for the Casketty romance we all crave more of. 

Once again, Castle managed to engage my brain with a brilliant mystery while tugging at my heartstrings with amazing characters. That's why I call them #HappyCastleMondays. 

C. Orlando was a TV Fanatic Staff Writer. Follow her on Twitter.