The Guys Behind 'Happy Death Day' Talk Time-Bending Ending & Sequel Ideas

Happy Death Day, out now in theaters, plays like a hilariously bloody Groundhog Day. That's intentional. "I wanted to take the horror movie and slasher movie tropes and turn them upside down," screenwriter Scott Lobdell tells Thrillist. "Every slasher film opens up with the mean girl getting killed and the good girl living till the end. And I thought, How can I make the mean girl and the good girl the same person?"

Death Day finds unlikable sorority girl Tree Gelbman (Jessica Rothe) waking up on her birthday... which also happens to be the same day a masked assailant kills her. The end is only the beginning for Tree, who, thanks to a time loop, continues to relive her big day over and over and over again. In other words, the general premise of Groundhog Day becomes a device our heroine uses to solve her own murder.

"Essentially, every [idea] has been done" before, director Christopher Landon says. "Every movie now is a combination of this movie and that movie and whatever. For me, it's always, Can this movie stand on its own? Even though it's the horror version of Groundhog Day, is it still its own thing?"

It is. In fact, Landon avoided watching Groundhog Day so it didn't speak too much to him during the production process. He pulled more inspiration from Halloween and John Hughes movies -- which explains the cheekiness sprinkled throughout Death Day. The heavy dose of humor takes the edge off Tree's meanness and helps the audience warm up to her. You eventually root for her, and you want her to become a better person. Like Phil in Groundhog Day, Tree begins to use the cycle to re-examine her priorities.

"I was dealing with a young [viewership] that hasn't seen Groundhog Day and that doesn't really know the ins and outs of [time-loop movies]," Landon says. "In this age of social media and all the crappy things that kids do to each other, I thought this was a nice movie with a good message for them -- and I could couch it in a fun, silly horror movie."

Tree's predicament unfolds as a 90-minute case of self-aware trial and error. The time loop restarts every time Tree dies -- so the rules of the loop are clear, especially with the precedent set by Groundhog Day. But why the loop is happening is a little murkier. Early drafts of the script had scientific theories explaining its existence. Others hinged on the unluckiness of October 13 as a potential trigger.

The theatrical cut nixes the theoretical science, leaving viewers to connect certain dots. Tree shares her birthday with her dead mom, for instance -- so is the time loop a gift from her guardian angel? That of a second chance? Or, as Tree wonders, is it all karma? She quickly realizes she's amassed countless enemies because of her selfishness. Does she deserve this hellish experience for how she's treated her peers? The reasoning is a bit up for interpretation, but the key is some form of atonement and betterment.

Landon says there was actually a point in pre-production when Universal was asking for an exact reason for the time loop; however, he fought back. He liked the lingering mystery, which, along with Tree's roster of haters, keeps viewers guessing till the end. If she stops her murder, does she stop the loop? "For me, it was about making sure there were enough credible red herrings and suspects," Landon says.

Unmasking the killer becomes a seemingly impossible task, as everyone around Tree looks like they could be out for some sort of revenge. It's fair to think Tree's love interest, Carter, could be guilty, for example. He's introduced as a spurned one-night stand with unclear intentions, and we don't immediately get his full back story. Same with Tree's professor fling, Gregory. And her other ex-fling. And her scores of sorority sisters. And, perhaps, the biggest red herring of them all: the murderous inmate being treated in the on-campus hospital. But after preemptively killing the inmate, Tree still wakes up on her birthday. It's a tragically comic gut punch, one that might make you ask, "Wait, why?" as it sends Tree back into her nightmare.

Tree's roommate, Lori -- initially the most innocuous of those in her inner circle -- is to blame. She's jealous of Tree's romance with Gregory. So she funnels her hatred into the poisonous cupcake Tree's gifted time and time again. Why did she die after killing the inmate? Tree finally pieces the puzzle together after the fake-out happy ending: The last thing she did before falling asleep was share the cupcake with Carter.

Solving the mystery and thwarting Lori stops the time loop, but it still doesn't fully explain why it happened. For that burning question, you'll have to hang your hopes on the future, like Lobdell and Landon.

"If I'm so lucky to get to make a sequel, and we would never count our chickens and I have no idea what's going to happen with this movie, I have the sequel ready," Landon says with a laugh. "It gets into the [time loop's] why, in a very, very, very, very specific way."

Sign up here for our daily Thrillist email and subscribe here for our YouTube channel to get your fix of the best in food/drink/fun.