<P> Waking up in Carter's bed again, Tree convinces Carter of her predicament by showing that she holds foreknowledge of the day's events . In Corky's, Tree admits to Carter that she does not like who she has become as she is distant from her father in the wake of her mother's death three years ago . Tree catches a local news report on John Tombs, a serial killer who is being held in the hospital on her campus . Concluding that Tombs is her killer, Tree rushes to the hospital to warn of his escape . Tombs breaks free and nearly kills Tree, but Carter follows and rescues her . Tombs snaps Carter's neck before chasing Tree to a nearby bell tower where she manages to subdue him with a crowbar . Realizing that Carter will remain dead if she doesn't restart the loop, Tree hangs herself in the tower . </P> <P> During the next iteration, Tree sets out to be a kinder person by ending her affair with Dr. Butler and meeting with her father to resolve her inner grief . That night, she prepares to stop Tombs . He manages to get the upper hand on her until Tree utilizes a campus - wide blackout that occurs during the loop to disarm him and shoot him to death . Relieved to finally be free, she celebrates her birthday in Carter's room and eats the cupcake given to her by Lori . </P> <P> However, the next morning Tree wakes up again on her birthday . Confused and distraught over the fact that killing Tombs did not stop the time loop, Tree returns to her room where Lori offers the cupcake again . Tree realizes that she had died in her sleep and also notes that this was the only time she had ever eaten the cupcake . Tree realizes that Lori is the true killer; Lori had poisoned the cupcake, but when Tree did not eat it, she utilized her job as a nurse in the hospital to frame Tombs for Tree's murder . Tree tries to coerce Lori to have a bite and when Lori refuses, Tree decides to take it to the police . Lori attacks Tree, locks the door and confesses that she was jealous of her affair with Dr. Butler . Tree manages to stuff the cupcake into Lori's mouth before kicking her out of a window, sending her falling to her death . Tree and Carter muse over the day's events back in the restaurant . He offers her his room for the night, also commenting her situation is a lot like the film Groundhog Day . Tree wakes up the next day believing herself to be in another loop, but it turns out to be a prank by Carter . The two share a kiss . </P> <Ul> <Li> Jessica Rothe as Theresa "Tree" Gelbman </Li> <Li> Israel Broussard as Carter Davis </Li> <Li> Ruby Modine as Lori Spengler </Li> <Li> Rachel Matthews as Danielle Bouseman </Li> <Li> Charles Aitken as Gregory Butler </Li> <Li> Rob Mello as John Tombs </Li> <Li> Phi Vu as Ryan Phan </Li> <Li> Caleb Spillyards as Tim Bauer </Li> <Li> Jason Bayle as David Gelbman </Li> <Li> Laura Clifton as Stephanie Butler </Li> <Li> Cariella Smith as Becky Shepard </Li> <Li> Tran Tran as Emily </Li> <Li> Blaine Kern III as Nick Sims </Li> <Li> Dane Rhodes as Officer Santora </Li> <Li> Tenea Intriago as Student Protestor </Li> <Li> Missy Yager as Mrs. Gelbman </Li> </Ul>

Who keeps killing tree in happy death day