Having survived the farcical but utterly life-threatening events in Happy Death Day (2017), the feisty sorority sister, Tree Gelbman, finds herself in the same college dorm, thankful to be alive. However, this time, it's Carter's roommate, Ryan, who claims that he is reliving the same paradoxical day over and over again, as a mysterious paranoid killer in a single-toothed baby-faced mask with a big kitchen knife has made a habit of murdering him. Under those circumstances, a valiant but vain attempt to face the challenge, once more, will send Tree back to square one, trapped in an all too familiar and blood-drenched time loop. How many deaths separate Tree from a truly happy birthday?