Israel Broussard and Jessica Rothe in Happy Death Day 2U.

Christopher Landon follows up his somewhat creative original Happy Death Day with Happy Death Day 2U, an overly ambitious sequel that starts off great, but gets lost in its second half.

Jessica Rothe returns as Tree, the college student who got stuck in the Groundhog Day murder loop in the original. The sequel starts with Ryan (Phi Vu), the character who walked in on Tree and Carter (Israel Broussard), stuck in a brand-new murder loop with a seemingly different baby-mask killer. Landon and friends establish a fascinating a reason for the whole murder-loop thing (a quantum-physics experiment) and set up some scenarios that openly acknowledge the plot of Back to the Future 2, featuring doppelgangers and everything. So far, so good.

Then the plot begins to center on Tree—specifically about her fixing other elements of her life, leaning hard on emotional stuff rather than the clever gimmicks of the film’s first half. In fact, the movie basically drops the doppelganger element completely, becoming just another murder-mystery that feels like a bad Scream sequel. Too bad.

At one point, I was looking at this movie as one of the greater sequel ideas I had ever witnessed. Then Landon squandered that idea and ultimately delivered a movie that feels like a copout.

Happy Death Day 2U is playing at theaters across the valley.