The final episode of Life On Mars airs tomorrow night on ABC. Sam Tyler's time-travel from 2008 to 1973 will be explained, and the show's producers say science-fiction fans will like the answers. Spoilers ahead...

We had an exclusive interview with Josh Appelbaum and Scott Rosenberg, producers of the U.S. version of Mars. And they promised that not only will the finale wrap up everything satisfactorily, but science fiction lovers will be thrilled.

The most amazing scene in last Wednesday's episode was the one where Sam gets up on the roof and prepares to jump, thinking it'll take him back to the present day. That's in the original BBC pilot, complete with the guy who's read Sam's psych file and is egging him on. And it was in the unaired David E. Kelley version of the pilot. But you didn't include it in the actual first episode. Why wait until the 16th episode to do that scene? Does it gain more weight because you waited so long?

Josh: You know what's funny, is that, we absolutely borrowed from the BBC, from the beginning to the end of this series. [But] that was a scene that actually kind of evolved naturally. I think the script had actually been written, and they were like, "Oh wait. This is just like that scene from the pilot." There have definitely been things that were conscious decisions to steal, as it were, from the BBC, but that wasn't one of them. [In fact, that scene came out of] our belief that you want the second to last episode of the season to feel like a season finale. And it's all about just trying to top that. The audience feels like it's cumulative, and it's crescendoing in the second-to-last episode, so how the fuck are they going to top themselves next week? And then we'll try to top ourselves, which we hope we did.

Scott: I really believe the back half of the season has been so much about Sam and Annie. The first half was about his mother and father, and those issues, [and] What am I doing here? In the back half, every episode just brought them closer and closer together, so I thought [that rooftop scene] was such a great moment. In fact I just wrote to Gretchen about that, because she does that thing she does in the pilot, where she puts his hand on her heart. And I was like, "Wow, Annie has come so far as a character in 16 episodes, from when she first put his hand on her heart, to that girl on the roof."

And also, we love and revere and have been cannibalizing the BBC all along, [but] we never considered putting that in the pilot - that thing on the roof. I actually think that was one of the rare missteps they made, in the [original BBC] pilot, was that thing on the roof. You hadn't earned it yet. Why is he jumping? Why would he even think? He just got there. He doesn't know anything about anything. Why would he think that jumping off the roof is going to take him home? Whereas by this point, with all the track that we laid, it kind of does make sense in episode 16.

It feels like Sam has been going to some really dark places in the past few episodes, what with going undercover and then believing that he might have committed murder. Is that continuing into the final episode?

Josh: Very much so, the finale if nothing else — I'm not even talking about the end moments of it, which reveal everything — but the finale is very much Sam, on a journey to recapture his humanity or lose it forever... The last few episodes play, and were conceived as, a three-parter in some ways, and they all sort of tie together...

Sam started to feel like it was liberating to be in the 1970s, like he could reinvent himself. In the midseason premiere, that Russian guy even tells him that being in a foreign country is a fresh start, and he takes that on board. But then it turns into him becoming more of a monster.

Scott: Absolutely. The whole fun of this is: Every time Sam sort of gets comfortable, it kind of bites him in the ass. The truth is he's living in a darker time, in many ways, the 1970s. One of the things we like is, that in order to embrace the people around him and the world he's in, it means embracing darkness. And then there's Annie who represents sort of the hope and light. The good news is, when you see Wednesday's episode, one wy or another, whether you love the ending or you hate the ending, I really believe it'll all make sense at least in terms of the emotional journey.

In the British version, it seems like Sam kind of loved it in the 1970s. In some ways, it was a happier, more fun time for him. You kind of have some of that, but at the same time it feels darker.

Josh: We'd hoped to be on the air for seven years, we wanted him to embrace this place as he did in the BBC, and for it to be a fun place he'd be okay living in. In wrapping up the series, we wanted to delve into the dark dimension of the story.

So you decided to go darker when you knew you weren't coming back?

Scott: No, basically, when our ratings started to suck we were all in really bad moods, so we naturally got darker and darker, as we were writing it. (Laughs.) We wanted to be in 1973.

So in the finale, we get more of an explanation for what's been going on? Including the little robots? How science fictional is it going to be?

Josh: Without saying too much, I don't think scifi fans will be disappointed.

Scott: That's for sure.

One thing that really blew us away in last week's episode was Sam's chemistry with Michael Imperioli. Especially where the two of them team up.

Josh: The Michael Imperioli of it all might be one of the great tragedies of the show not being able to move forward. You see those two guys partnered up for a beat or two in that episode, It was so much fun. Having that as a primary element, we could have gotten seven more years. We could have been writing those scenes happily.

Scott: Even the episode where [Ray] and Annie sort of partner up. I just remember, after watching that first cut, thinking "We've got to do more episodes featuring the two of them. They were amazing together."

What are some other things you would have done if you'd gotten a season two?

Scott: As with any first season, you learn what works and what doesn't work. I think it's not a mystery that this last run of episodes has been so strong. We figured out the sweet spot. We don't have to put so much weight on the crime of the week. It's striking so much balance between the mythology and the 1973 and the cases and the cops. I think some of my favorite stuff at the end of the day has just been two characters talking.