If you think all stories about time travel are complicated, think again.
When Timeless creators Eric Kripke and Shawn Ryan set out to plan how their NBC time travel series was going to deal with the complicated sci-fi trope, their first goal was to make it easy for viewers to follow along.
"Mostly we're striving for simplicity within our rules," Kripke tells The Hollywood Reporter. "We're really aiming to be fun, romantic, a throwback to the kind of time travel story that was simpler and more thrilling. Things like Quantum Leap or Back to the Future or the old-school show Voyagers! There's been some civic mandate over the last 10 or 15 years that time travel stories could only be mindf - s, and we don't really want to do that."
But Ryan is quick to interject that their show will still have deep layers to it - a sentiment that Kripke echoes.
"It's not that we don't have rules and it's not that our world isn't complicated, it's just that we're really striving to keep things as basic as possible," Kripke says. "We have this main rule that we're really operating under which is that you can never travel back to a period that you've already been. The reason we came up with that rule was to keep things simple and to keep the story propulsive and moving forward."
The premiere episode finds a team comprised of historian Lucy Preston (Abigail Spencer), soldier Wyatt Logan (Matt Lanter) and scientist Rufus Carlin (Malcolm Barrett) time-traveling back to the Hindenburg disaster to stop the mysterious Garcia Flynn (Goran Visnjic) from changing history.
"Spoiler alert: They don't catch Garcia Flynn at the Hindenburg," Kripke says. "The rules of the show are that you can't just go back to the Hindenburg again and try it all over again. You have to move to the next time period. What we're trying to avoid is the overly complicated time travel trope where you're meeting slightly older and slightly younger versions of yourself, or there are like 19 versions of yourself re-creating the story over and over again."
Kripke pauses to laugh, and adds, "As we say in the writers room, you want to be Back to the Future, not Back to the Future 2."
Another rule the Timeless team is following is the "Butterfly Effect."
"The universe of our show operates on one single timeline," Ryan says. "There aren't multiverses or alternate realities and dimensions. Just one timeline. If you go back into the past and you make a change, that change ripples forward and affects the present. Our heroes try to stop those ripples from happening or they keep them as small as possible."
The reason why Kripke and Ryan wanted to keep the time travel rules as simple as possible was to make sure they don't have their actors pulling double or triple duty as older or younger versions of themselves.
"We knew from the start that we didn't want to do that complicated trope where you have four different Lucy's running around four different locations in the same story," Ryan says. "We wanted to keep it easier than that."
Kripke adds, "As much as I passionately love the movie Looper, we didn't want to do Looper where there's an older version of Lucy meeting a younger version of Lucy. And if you kill the younger version of Lucy it affects the older version of Lucy. We wanted to keep doubles out of the story."
Read more: 'Timeless': TV Review
Another major rule for the series is that they're not moving forward in time.
"At least for now, the time machine is only traveling to the past, not to the future," Kripke says. "We look at this show as more historical adventure and romance and character-driven than a sci-fi show. We're not interested at the moment in seeing the future."
When creating a show entirely about traveling through time, Ryan and Kripke have run into a few recurring issues, but none they say that is insurmountable.
"Our biggest challenge is less to do with the time travel aspect, since we keep it so simple, and more to do with when we go back to different parts of history. You can't always change facts to what you would want them to be for the story," Ryan says. "Some things you can, and we allow ourselves to do that. But for the most part, we're trying to stay fairly true to the big parts of history. Sometimes that requires more work to make it fit into your story."
He pauses to think, and then continues, "And the most difficult thing is keeping track of what has changed. What is the universe we are coming back to episode after episode as things change? Keeping track of all that stuff and making sure we're not violating something we established in an earlier episode, that is going to become a bigger problem should we get a back nine or a second or third season."
Both Ryan and Kripke are well aware that time travel shows are a trend among the crop of new series, but they're not worried about getting lost in the shuffle.
"One way that we stand out is that our network had the confidence to put us on in the fall," Ryan says with a laugh. "I don't know about those other ones. I know I've heard of them, but I don't think the American viewing public has even heard of them yet."
"The viewing public will have already decided how they feel about our show by the time those other ones finally premiere," Kripke adds. "We will rise or fall on our own before any of those other ones even come into play."
According to Ryan, theirs is also different from all the rest based on how they present their time travel stories.
"I have a feeling those other ones won't be going to a different time period each week like we are," Ryan says. "We're unique in that regard. And television is more about execution than anything else like concept. Concept gets your attention, but execution and characters are what make or break a television show."
Timeless airs Mondays at 10 p.m. on NBC.