Coherence

Eight friends gather for a dinner party in California on a night when a comet passes by. During the dinner, Kevin proposes a business trip to Vietnam to Emily, but she hesitates to respond affirmatively.

The atmosphere becomes tense as Kevin's ex-girlfriend, Laurie, attends the gathering. She expresses her desire to rekindle her relationship with Kevin, complicating the evening further.

Suddenly, a power outage occurs, leaving the friends in darkness. The hosts provide glow sticks for light, and they opt for blue glow sticks to guide them during the confusion.

Noticing that one house up the street still has power, the group decides to venture outside. Upon their return, they find a broken glass and a mysterious box containing personal items from another version of themselves.

The friends come to the shocking realization that the other house represents an alternate version of their own reality. They discover photos of themselves with strange numbers on the back, prompting further investigation.

Emily begins to write down the numbers in an attempt to find a meaningful pattern, though their efforts lead to confusion. This sparks a discussion about the strange occurrences they are experiencing.

The friends venture to the other house, where they come face to face with their doubles holding red glow sticks. The encounter is shocking and leads to a frantic retreat back to the safety of their own home.

Hugh examines his physics notes and realizes that the comet has caused a split in reality, with one reality doomed to collapse. This revelation creates tension and fear among the group.

With rising paranoia, Mike suggests preemptively eliminating their doubles to ensure their survival. The group debates this extreme plan while considering ways to outsmart their counterparts.

As tension escalates, they mock up a plan to leave markers outside their houses to connect the realities. They compile numbers on a notepad but realize inconsistencies in their memories regarding these numbers.

The situation worsens when a blackmail note appears, leading to paranoia about a potential dark version of themselves. This heightens tension and fear in an already fraught atmosphere.

Emily succumbs to desperation and ventures into different realities, seeking a version of her life devoid of conflict. She discovers a version of herself that is happy and decides to take drastic action.

Emily lures her double outside by shattering a car window and attempts to incapacitate her. However, the plan backfires, leading to a tense struggle in which Emily must fight to maintain control.

After subduing her double, Emily wakes up the next day in a seemingly normal reality. However, the unease persists when Kevin receives a mysterious call from Emily's number, leaving both of them in a state of suspicion.