At the beginning of The Tomorrow People's freshman season, the CW drama's creator Phil Klemmer promised a coming of age tale. And now with the season finale, the writer is looking to press the show into a more grown up action adventure.

After 21 episodes of double crosses, family revelations and battles between the titular evolved teenagers and the clandestine organization known as Ultra, series lead Stephen (Robbie Amell) is set to make up for the mistakes of his scientist father all while his uncle Jedekiah (Mark Pellegrino) uses his newfound power to tear the world apart. And while that conflict has been brewing for a while, Klemmer promised even more big changes as the show turns the page towards what he hopes is a very different, adult Season 2 pickup.

In advance of tonight's season finale – the aptly titled "Son of Man" – Spinoff spoke to the executive producer and head writer about the changes in character and story he's discovered over The Tomorrow People's first season, why Jedekiah and other characters will lose it all (including, perhaps, their lives) in the finale and how he plans to write a brand new pilot for a brand new year if the network gives the drama a Season 2.

Spinoff Online: At the beginning of the season, you talked about Stephen's coming of age story as a driving concern for you in The Tomorrow People. Now after 22 episodes, has that story turned out as you expected, or has it changed in any way?

Phil Klemmer: For Stephen's story, I think it turned out the way I envisioned it. Certain other characters surprised me, but I always had a pretty firm grasp on that. For him to grow up, I knew that there was this paradigm where you had to know your father and then lose your father to inherit the mantle. I knew that Stephen's attempt to reunite his family was going to be in vein. As we enter the finale, we see that his mom and brother are on the lam, and essentially Stephen is a man. He started this as a high school kid, and all his questions were about who he was or what he was. But as we go into the finale, he's answered all these questions, and the only one yet to be answered is "What is he going to do?" Now that he knows all he does about who he is and what his father was and how his father failed, it all comes together. His father, even though he was a Tomorrow Person, ultimately was a failure, and now it's up to Stephen alone to succeed where Roger did not.

The last run of episodes have turned into one massive arc exploring the final battle between the Tomorrow People and Ultra. What did that shift away from episodic stories and towards epic ideas offer you as a writer?

There's a lot of trial and error in television. Before you get to know your characters as well as we now have, you're obliged to use incidents to move the plot along. But as the characters start to become more complicated and the audience can appreciate the nuances, you can start fill a lot of pages just with the people you know. We really moved away from the "bad guy of the week" shape and into something much more serialized and much more focused on our characters. And that's because we cared about our characters so much. Not to be cheeky, but that's evolution. That's the evolution of drama, and we've got our writers and our cast to thank for that.

To make a cheeky transition, let's talk about Jedekiah's evolution in the last few episodes. Last week, we ended with him as a kind of Tomorrow Person in overdrive as he used his new powers to flip over police cars. How does that big turn ultimately change a character who seems to have changed a lot over the past few episodes?

To me, I never meant to give a message to the audience but instead just tell a story. But in the age we all live in now, I think we can see that playing God with the planet will have dangerous and inexorable consequences for human survival. And so for Jedekiah, he's always made his whole life about doing the right thing in protecting humankind from the threat of this rival species. Now obviously at the end of episode 21, he wants these powers not for selfish reasons – as we explored in his backstory he's got pretty pure reasons – but playing God like that never turns out as you want. It's too complicated for that. So when he steals Eileen's powers and gives them to himself, we see that flicker of omnipotence in his eye and in that smile he cracks. In the finale, we'll see the consequences come cracking down on Jedekiah, and you'll feel bad for the guy. Because he's trying to save us, and in the process he's pretty much going to lose everything.

There's been a lot of talk about whether the show will return for a Season 2, and I know also that there are some big changes, including a number of deaths, set to hit in this finale. Researching the original UK Tomorrow People, I was struck by how it seemed to reinvent itself with each new season. How will your last episode of the season turn the setup of the show towards another direction like that?

For me, I always see finales as finales. I don't like the ones where the first half is a resolution and the second half is sort of a half-baked promise. We spend that majority of the finale wrapping things up. We've got so many balls in the air that it's all we can do to catch them. But the tiny bit of a teaser we see at the end of this episode makes it clear that we could never return to this world in the same way again. That wasn't because of the original Tomorrow People that we decided to do that. It's just that to me, it's more interesting. We're not going to be like True Detective where we swap out characters, but basically everything except the characters – or the characters who actually live – is going to change in Season 2. We're going to jump ahead in time. We're going to see Stephen as a man because I feel like he's a man dramatically at the end of this season. We'll jump forward into his future and see what his life becomes, and we'll have new mythology and a new big bad. The Tomorrow People won't be living in the lair anymore. The way we blow things up at the end of the finale makes it clear that we can never go home again. And for me thinking about [the season two premiere], I want to write another pilot for The Tomorrow People, and that's how I'm looking at the first episode of Season 2.

The Tomorrow People's finale debuts Monday at 9:00 Eastern and Pacific on The CW.