James Daniel Stern is a theoretical physicist whose work consumes most of what he is and hopes to become. His only real connections are with his sister Meredith Tommie-Amber Pirie and with another scientist named Courtney Cleopatra Coleman. On his way to visit Meredith, he is abducted by his Uber driver who claims to be his future self and warns him away from pursuing his research. James remains skeptical, even as the promise of breakthrough results whispers in his ear, and he discovers that his research supervisor Dr. Rowley Frances Conroy is about to gain access to a particle accelerator essential to proving his theories.
Future James (" Jimmy ") Daniel Stern tries to warn James that the obsession will ruin his life. He urges him to seize the moment, to live more fully, and even teaches him a basic practice like meditation in a bid to loosen the grip of the future on the present.
Meredith Tommie-Amber Pirie is also trying to coax James to face the death of their parents fifteen years earlier and to finally spread their ashes. Meanwhile, Courtney Cleopatra Coleman is preparing to depart for a new chapter at the Large Hadron Collider in CERN, Switzerland, a move that could pull her away from the close-knit work they share.
Encouraged by Jimmy, James attempts to loosen his fixation on what lies ahead, but his determination to push forward with the research remains strong. Jimmy explains that the time travel he offers only allows going backward, and that James must endure the waiting period in isolation to return to the present. He adds a pointed note: if James had truly changed, he wouldn’t still be there.
James does open up about his feelings for Courtney, mustering the courage to ask her out on a date, but when she sparks him with inspiration for his work the moment slips away. She soon packs for Switzerland, leaving James more resolved than ever to see his project through, even as personal connections fray.
Dr. Rowley Frances Conroy is poised to publicly commit to their new research initiative, intensifying the pressure and heightening the stakes in the lab. Driven to a desperate edge, Jimmy attacks: he shoots her through the hand with a crossbow and pursues her through the facility.
Rather than attend the big announcement, James seeks quiet by the lake, meditating as a way to find a new path forward. In a pivotal turn, he realizes he must change, and that realization causes Jimmy to fade to dust just before he can do real harm to Dr. Rowley.
The story closes on a quiet note in a cafe, where James sits with a puppy on his lap. Courtney joins him, sharing a croissant, and says, "I can't believe you're here." The other patrons in the café — shown to be different versions of James, Courtney, and the dog from various moments in time — hint at the film’s exploration of time, memory, and the many roads a life can take.
> I can't believe you're here.
