'Hawaii Five-0' Boss on the Emotional Series Finale and McGarrett's Surprise Reunion (Exclusive)

ET talks to showrunner Peter Lenkov about Friday's swan song and why it was the right time to go.

Warning: If you haven't watched Friday's series finale of Hawaii Five-0do not proceed. You are entering spoiler territory.

Aloha, Hawaii Five-0.

CBS' long-running action drama signed off on Friday after a 10-season run, giving Five-0 team leader Steve McGarrett (Alex O'Loughlin) the closure he had been seeking since he first came to the island nearly a decade ago to form the Task Force. After nearly losing his best friend and partner, Danny "Danno" Williams (Scott Caan), McGarrett sought the answers he was looking for in his father's death, closing one chapter while opening another. It was time for him to leave Hawaii... for now.

As McGarrett boarded the plane in his search for "peace," he received a surprise big enough to turn his world upside down (in a good way). Catherine (Michelle Borth), McGarrett's true love, magically appeared in the empty seat beside him and everything clicked into place. (After all, it was Catherine who helped crack the case that saved Danny's life.)

"You ready?" Catherine asked as she took the seat next to him. "Yeah," McGarrett replied, taking her hands in his. Where are they off to? And what is McGarrett in search of? After Friday's swan song, ET spoke with showrunner Peter Lenkov to break down the final episode of Hawaii Five-0, from the team's emotional goodbyes to McGarrett's long overdue reunion with Catherine, and whether this truly is the end of the road for the Five-0 team.

ET: When did it become apparent that this would be the last season of Hawaii Five-0

Peter Lenkov: Honestly, I think every season I go into it thinking that it possibly could be the last season. And Season 10, it felt right to everybody. Alex [O'Loughlin], Scott [Caan], the actors, everybody at the network just thought, "OK." It just felt right. I mean, maybe it's a gut instinct. When the network called, we just felt like it was the right thing to do.

The series finale brought McGarrett full circle. What was top of mind for what you were hoping for in terms of the perfect ending for this character?

For me, I always thought that the way Steve and Danny met and the conflict between those two from the first time they met in that garage -- the fact that they hated each other and were forced to work together. And 10 years later, Steve's sitting by his bedside or he's saying, "God, take me, not him," you see how far that relationship has come and how close these two men are. That arc was really a big part of the success of the show; watching those two guys grow so fond of each other. That ingredient was always a part of the endgame for me, to really show how far they've come as a team.

Karen Neal/CBS

I think McGarrett has always hit the ground running. We saw him in the pilot come in on a military plane land and hit the ground running, moving, always forward, never looking back. The idea of him leaving the island for a moment and decompress and get re energized and rejuvenated, and hopefully off-screen, I imagine people will hopefully believe that he'll come back at some point and spur a new chapter. Maybe with a family with Catherine and maybe continuing to run the task force. Maybe not as hands on, but the idea was to have him in the Adirondack chairs sitting out with Danny, there's a lot of connected tissue to that first episode. I wanted to show how far everything has come. McGarrett has always suffered from post-traumatic stress. He played that over 10 years and it's finally caught up with him. He needs a little bit of a break. I wanted to play a natural closure that felt real and honest, and I didn't want to manufacture a reason for the show to end. I want it to end on something that we've been building to over 10 years and that felt like the right thing to do.

McGarrett and Danny's conversation outside on the beach when they say their goodbyes was bittersweet, but the individual goodbyes the rest of the Five-0 team had for McGarrett was deeply emotional. Was all of that all on the page? What was the hardest goodbye to craft?

The goodbye scene with all the characters in the house, that was something that was more ad-libbed than anything. That was shot two hours after I told the cast and the crew that the show was not coming back for season 11. So that was one take -- very raw and honest with no real edits. Everybody in their own words saying goodbye, to not just McGarrett but to Alex and the rest of the show. So what you're seeing there is someone pointed a camera and let these people express themselves and release a real honest emotion with regards to the show ending. That really was not scripted. In the script, it was more about what McGarrett meant to all of them but the words were the actors. I think that's why it's so strong, is because it's really coming from the heart and it feels natural. It doesn't feel like scripted lines. It feels like people really sharing an honest emotion.

Was it always the plan to bring Catherine back for this final episode so McGarrett could have hope for his future?

For me, Catherine was not as complicated as other people think she is. I think she's somebody like McGarrett; she's a soldier and she's always put God and country first. It was not her choice to do some of the things that she did. Some of the things that hurt him were not things that she would have done if it wasn't something that she was asked to do. I think that she's always loved him and he's always loved her. I've always thought from the time the character was introduced that he would end up with her. It was just a matter of when, but I always thought that. If you've seen William Goldman's movie, Butch Cassidy and the Sundance Kid, it's Butch and Sundance and Katharine Ross [who played Sundance's lover Etta Place]. That's how I see the next chapter of their life. It's McGarrett coming back with Catherine and Danny, and it's that sort of triangle -- the bromance and the romance -- that would take them into their later years.

Karen Neal/CBS

Did you have any considerations about bringing back Daniel Dae Kim and Grace Park for the series finale or did you feel like that door closed in terms of story?

I didn't, honestly. I didn't really think about it. I felt like they haven't been a part of their show for so long. I talk to Grace, not regularly, but pretty often and she's spectacular and she's on another show [ABC's A Million Other Things], so I don't even know even if I thought about it if it could have worked out. But if I did that, it would come out of the blue, all of a sudden them showing up and saying goodbye. I really felt like the way the show holds together, the minutes felt very real and very organic. Again, I'm thinking about this in hindsight, if I had thought about that, I wonder if that would've felt wedged in and gimmicky. It's a good question. I wish I was smart enough to have thought about it before. All I wanted to do was do a very honest, emotional goodbye episode.

What was the final scene that was shot?

The goodbye scene was shot pretty early. The last few scenes where the [Adam] and Quinn scenes. Those were the last to be shot in the episode. But I'll tell you something interesting, and I've never had this experience before on any show, but it shows the way this crew has grown as a family for 10 years. When I told the cast and the crew that we were not coming back, I had them all everybody gathered around inside the HQ and one by one people said, "Do you mind if I say something?" And people would step forward and talk about what an impact the show had on them. The fact that they were able to support their families for 10 years, and how meaningful it was... I never had that experience. Usually on a show your crew goes from show to show, but this was a big part of their lives. It's a big part of the fabric of that island. It's only a million people on Oahu, so everybody knows somebody that's connected to Five-0. I really was emotional for me knowing what an impact we had there. It wasn't just a show, it was a source of pride for people.

You've had crossovers with other CBS shows like MacGyver and Magnum P.I. Is there a chance we could see Five-0 characters still pop in on these other shows? 

That's definitely the plan.

Is there anything else you wanted to say about wrapping up the show?

We're very lucky. Reboots don't usually go this long and I think that it's attributed to good casting. People really love those characters and I feel very lucky because this thing really could have ended very, very early on -- and it didn't. And just very lucky. We had a very loyal fanbase that followed us around, and they seem pretty devastated that we're leaving, which tells me we did our job so I'm happy about that.

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